Terminal apparatus and communication method

ABSTRACT

To provide a terminal apparatus and a communication method capable of improving reliability and frequency efficiency in a case of transmission by beamforming. Provided are a higher layer processing unit configured with demodulation reference signal (DMRS) antenna port groups for indicating two groups of antenna ports of a DMRS, a receiver configured to receive the DMRS, downlink control information (DCI), and a downlink shared channel (PDSCH), and a decoding unit configured to decode the PDSCH, wherein the PDSCH includes a transport block, and in a case that the number of the transport blocks configured in the DCI is one, the PDSCH demodulated using a DMRS of a first group and/or the PDSCH demodulated using a DMRS of a second group is used to decode one transport block.

TECHNICAL FIELD

The present invention relates to a terminal apparatus and acommunication method. This application claims priority based on JP2018-205076 filed on Oct. 31, 2018, the contents of which areincorporated herein by reference.

BACKGROUND ART

Research and development activities related to the 5th generation mobileradio communication system (5G system) have been actively carried out,aiming to start commercial services around the year 2020. A visionrecommendation on the standard system of the SG system (Internationalmobile telecommunication—2020 and beyond: IMT-2020) was recentlyreported (see NPL 1) by the International Telecommunication Union RadioCommunications Sector (ITU-R), which is an international standardizationbody.

Ensuring frequency resources is an important challenge for acommunication system to address rapid increase of data traffic.Therefore, in 5G, it is one of the targets to achieve ultra-largecapacity communications using higher frequency bands than the frequencybands used in Long term evolution (LTE). However, in wirelesscommunication using high frequency bands, pathloss is a problem. Inorder to compensate for pathless, beamforming by multiple antennas is apromising technique (see NPL 2).

CITATION LIST Non Patent Literature

NPL 1: “IMT Vision—Framework and overall objectives of the futuredevelopment of IMT for 2020 and beyond,” Recommendation ITU-R 2083-0,September 2015.

NPL 2: E. G. Larsson, O. Edfors, F. Tufvesson, and T. L. Marzetta,“Massive MIMO for next generation wireless system,” IEEE Commun. Mag.,vol. 52, no. 2, pp. 186-195, February 2014.

SUMMARY OF INVENTION Technical Problem

However, beamforming especially in high frequency bands may lead to aproblem in reliability, frequency efficiency, or throughput,specifically a cutoff of a channel by blocking of a person or an object,or, a low-rank communication for example, due to high spatialcorrelation in Line of Sight (LOS) environments.

An aspect of the present invention has been made in view of suchcircumstances, and an object of the present invention is to provide abase station apparatus, a terminal apparatus, and a communication methodcapable of improving reliability, frequency efficiency, or throughput ina case that the base station apparatus or the terminal apparatusperforms beamforming transmission.

Solution to Problem

To address the above-mentioned drawbacks, a terminal apparatus and acommunication method according to an aspect of the present invention areconfigured as follows.

A terminal apparatus according to an aspect of the present inventionincludes: a higher layer processing unit configured with demodulationreference signal (DMRS) antenna port groups for indicating two groups ofantenna ports of a DMRS; a receiver configured to receive the DMRS,downlink control information (DCI), and a downlink shared channel(PDSCH); and a decoding unit configured to decode the PDSCH, wherein thePDSCH includes a transport block, and in a case that the number of thetransport blocks configured in the DCI is one, the PDSCH demodulatedusing a DMRS of a first group and/or the PDSCH demodulated using a DMRSof a second group is used to decode one transport block.

In a terminal apparatus according to an aspect of the present invention,in a case that the number of the transport blocks configured in the DCIis two, a first transport block is decoded in the PDSCH demodulatedusing the DMRS of the first group, and a second transport block isdecoded in the PDSCH demodulated using the DMRS of the second group.

In a terminal apparatus according to an aspect of the present invention,in a case that the number of DMRS antenna ports indicated in the DCI isequal to or greater than a prescribed number, a first transport block isdecoded in the PDSCH demodulated using the DMRS of the first group, anda second transport block is decoded in the PDSCH demodulated using theDMRS of the second group.

A communication method according to an aspect of the present inventionis a communication method for a terminal apparatus, the communicationmethod including the steps of: configuring, by a higher layer,demodulation reference signal (DMRS) antenna port groups for indicatingtwo groups of antenna ports of a DMRS; receiving the DMRS, downlinkcontrol information (DCI), and a downlink shared channel (PDSCH); anddecoding the PDSCH, wherein the PDSCH includes a transport block, and ina case that the number of the transport blocks configured in the DCI isone, the PDSCH demodulated using a DMRS of a first group and/or thePDSCH demodulated using a DMRS of a second group is used to decode onetransport block.

Advantageous Effects of Invention

According to an aspect of the present invention, by the base stationapparatus or the terminal apparatus communicating by beamforming, it ispossible to improved reliability, frequency efficiency, or throughput.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a communication systemaccording to the present embodiment.

FIG. 2 is a block diagram illustrating a configuration example of a basestation apparatus according to the present embodiment.

FIG. 3 is a block diagram illustrating a configuration example of aterminal apparatus according to the present embodiment.

FIG. 4 is a diagram illustrating an example of a communication systemaccording to the present embodiment.

DESCRIPTION OF EMBODIMENTS

A communication system according to the present embodiment includes abase station apparatus (a transmitter, a cell, a transmission point, agroup of transmit antennas, a group of transmit antenna ports, componentcarriers, an eNodeB, gNodeB, a transmission point, a transmission and/orreception point, a transmission panel, an access point, and a subarray)and a terminal apparatus (a terminal, a mobile terminal, a receptionpoint, a reception terminal, a receiver, a group of receive antennas, agroup of receive antenna ports, a UE, a reception point, a receptionpanel, a station, and a subarray). A base station apparatus connected toa terminal apparatus (base station apparatus that establishes a radiolink with a terminal apparatus) is referred to as a serving cell.

The base station apparatus and the terminal apparatus in the presentembodiment can communicate in a licensed band and/or an unlicensed band.

According to the present embodiments, “X/Y” includes the meaning of “Xor Y”. According to the present embodiments, “X/Y” includes the meaningof “X and Y”. According to the present embodiments, “X/Y” includes themeaning of “X and/or Y”.

FIG. 1 is a diagram illustrating an example of a communication systemaccording to the present embodiment. As illustrated in FIG. 1, thecommunication system according to the present embodiment includes a basestation apparatus IA and a terminal apparatus 2A. Coverage 1-1 is arange (a communication area) in which the base station apparatus 1A canconnect to the terminal apparatuses. The base station apparatus 1A isalso simply referred to as a base station apparatus. The terminalapparatus 2A is also simply referred to as a terminal apparatus.

With respect to FIG. 1, the following uplink physical channels are usedfor uplink radio communication from the terminal apparatus 2A to thebase station apparatus 1A. The uplink physical channels are used fortransmitting information output from a higher layer.

-   -   Physical Uplink Control Channel (PUCCH)    -   Physical Uplink Shared Channel (PUSCH)    -   Physical Random Access Channel (PRACH)

The PUCCH is used to transmit Uplink Control Information (UCI). TheUplink Control Information includes a positive Acknowledgement (ACK) ora Negative Acknowledgement (RACK) (ACK/NACK) for downlink data (adownlink transport block or a Downlink-Shared Channel (DL-SCH)),ACK/NACK for the downlink data is also referred to as HARQ-ACK or HARQfeedback.

Here, the Uplink Control Information includes Channel State Information(CSI) for the downlink. The Uplink Control Information includes aScheduling Request (SR) used to request an Uplink-Shared Channel(UL-SCH) resource. The Channel State Information refers to a RankIndicator (RI) for specifying a preferable spatial multiplexing order, aPrecoding Matrix Indicator (PMI) for specifying a preferable precoder, aChannel Quality Indicator (CQI) for specifying a preferable transmissionrate, a CSI-Reference Signal (RS) Resource Indicator (CRI) forspecifying a preferable CSI-RS resource, a Reference Signal ReceivedPower (RSRP) measured by a CSI-RS or a Synchronization Signal (SS), andthe like.

The Channel Quality Indicator CQI (hereinafter, referred to as a CQIvalue) can be a preferable modulation scheme (e.g., QPSK, 16 QAM, 64QAM, 256 QAM, or the like) and a preferable coding rate in a prescribedband (details of which will be described later). The CQI value can be anindex (CQI index) determined by the above modulation scheme, codingrate, and the like, The CQI value can take a value predetermined in thesystem.

The CRI indicates a CSI-RS resource whose received power/receivedquality is preferable from multiple CSI-RS resources.

Note that the Rank Indicator and the Precoding Quality indicator cantake the values predetermined in the system. The Rank Indicator and thePrecoding Matrix Indicator can be an index determined by the spatialmultiplexing order and Precoding Matrix information. Note that some orall of the CQI value, the PMI value, the RI value, and the CRI value arealso collectively referred to as “CSI values”.

A PUSCH is used for transmission of uplink data (an uplink transportblock, UL-SCH). The PUSCH may be used for transmission of ACK/NACKand/or Channel State Information along with the uplink data. The PUSCHmay be used to transmit the uplink control information only.

The PUSCH is used to transmit an RRC message, The RRC message is asignal/information that is processed in a Radio Resource Control (RRC)layer. The PUSCH is used to transmit an MAC Control Element (CE). Here,MAC CE is a signal/information that is processed (transmitted) in aMedium Access Control (MAC) layer.

For example, a power headroom may be included in MAC CE and may bereported via PUSCH. In other words, a MAC CE field may be used toindicate a level of the power headroom.

The PRACH is used to transmit a random access preamble.

In the uplink radio communication, an Uplink Reference Signal (UL RS) isused as an uplink physical signal. The uplink physical signal is notused for transmission of information output from higher layers, but isused by the physical layer. The Uplink Reference Signal includes aDeModulation Reference Signal (DMRS), a Sounding Reference Signal (SRS),and a Phase-Tracking reference signal (PT-RS).

The DMRS is associated with transmission of the PUSCH or the PUCCH. Forexample, the base station apparatus 1A uses DMRS in order to performchannel compensation of PUSCH or PUCCH. For example, the base stationapparatus IA uses SRS to measure an uplink channel state. The SRS isused for uplink observation (sounding). The PT-RS is used to compensatefor phase noise. Note that a DMRS of the uplink is also referred to asan uplink DMRS.

In FIG. 1, the following downlink physical channels are used for thedownlink radio communication from the base station apparatus 1A to theterminal apparatus 2A. The downlink physical channels are used fortransmitting information output from the higher layer.

-   -   Physical Broadcast Channel (PBCH)    -   Physical Control Format Indicator Channel (PCFICH)    -   Physical Hybrid automatic repeat request (HARQ) Indicator        Channel (PHICH)    -   Physical Downlink Control Channel (PDCCH)    -   Enhanced Physical Downlink Control Channel (EPDCCH)    -   Physical Downlink Shared Channel (PDSCH)

The PBCH is used for broadcasting a Master Information Block (MIB, aBroadcast Channel (BCH)) that is used commonly by the terminalapparatuses. The PCFICH is used for transmission of information forindicating a region (e.g., the number of Orthogonal Frequency DivisionMultiplexing (OFDM) symbols) to be used for transmission of PDCCH. Notethat the MIB is also referred to as a minimum system information.

The PHICH is used for transmission of ACK/NACK with respect to uplinkdata (a transport block, a codeword) received by the base stationapparatus 1A. In other words, the PHICH is used for transmission of aHARQ indicator (HARQ feedback) for indicating ACK/NACK with respect tothe uplink data. Note that ACK/NACK is also called HARQ-ACK. Theterminal apparatus 2A reports ACK/NACK having been received to a higherlayer. ACK/NACK refers to ACK for indicating a successful reception,HACK for indicating an unsuccessful reception, and DTX for indicatingthat no corresponding data is present. In a case that the PHICH foruplink data is not present, the terminal apparatus 2A reports ACK to ahigher layer.

The PDCCH and the EPDCCH are used to transmit Downlink Control.Information (DCI). Here, multiple DCI formats are defined fortransmission of the downlink control information. To be more specific, afield for the downlink control information is defined in a DCI formatand is mapped to information bits.

For example, as a DCI format for the downlink, DCI format 1A to be usedfor the scheduling of one PDSCH in one cell (transmission of a singledownlink transport block) is defined.

For example, the DCI format for the downlink includes downlink controlinformation such as information of PDSCH resource allocation,information of a Modulation and Coding Scheme (MCS) for PDSCH, and a TPCcommand for PUCCH. Here, the DCI format for the downlink is alsoreferred to as downlink grant (or downlink assignment).

For example, as a DCI format for the uplink, DCI format 0 to be used forthe scheduling of one PUSCH in one cell (transmission of a single uplinktransport block) is defined.

For example, the DCI format for the uplink includes uplink controlinformation such as information of PUSCH resource allocation,information of MCS for PUSCH, and a TPC command for PUSCH. Here, the DCIformat for the uplink is also referred to as uplink grant (or uplinkassignment).

The DCI format for the uplink can be used to request Channel StateInformation (CSI; also referred to as reception quality information) forthe downlink (CSI request).

The DCI format for the uplink can be used for a configuration forindicating an uplink resource to which a CSI feedback report is mapped,the CSI feedback report being fed back to the base station apparatus bythe terminal apparatus. For example, the CSI feedback report can be usedfor a configuration for indicating an uplink resource that periodicallyreports Channel State Information (Periodic CSI). The CSI feedbackreport can be used for a mode configuration (CSI report mode) forperiodically reporting the Channel State Information.

For example, the CSI feedback report can be used for a configuration forindicating an uplink resource that reports aperiodic Channel StateInformation (Aperiodic CSI). The CSI feedback report can be used for amode configuration (CSI report mode) for aperiodically reporting theChannel State Information.

For example, the CSI feedback report can be used for a configuration forindicating an uplink resource that reports semi-persistent Channel StateInformation (semi-persistent CSI). The CSI feedback report can be usedfor a mode configuration (CSI report mode) for reporting thesemi-persistent Channel State Information. Note that the semi-persistentCSI report is periodically reporting CSI in a period since activatedwith higher layer signaling or downlink control information untildeactivated.

The DCI format for the uplink can be used for a configuration forindicating a type of the CSI feedback report that is fed back to thebase station apparatus by the terminal apparatus. The type of the CSIfeedback report includes wideband CSI (e.g., Wideband CQI), narrowbandCSI (e.g., Subband CQI), and the like.

In a case that a PDSCH resource is scheduled in accordance with thedownlink assignment, the terminal apparatus receives downlink data onthe scheduled PDSCH. In a case that a PUSCH resource is scheduled inaccordance with the uplink grant, the terminal apparatus transmitsuplink data and/or uplink control information on the scheduled PUSCH.

The PDSCH is used to transmit the downlink data (the downlink transportblock, DL-SCH). The PDSCH is used to transmit a system information blocktype 1 message. The system information block type 1 message iscell-specific information.

The PDSCH is used to transmit a system information message. The systeminformation message includes a system information block X other than thesystem information block typeb 1. The system information message iscell-specific information.

The PDSCH is used to transmit an RRC message. Here, the RRC messagetransmitted from the base station apparatus may be shared by multipleterminal apparatuses in a cell. The RRC message transmitted from thebase station apparatus 1A may be a dedicated message (also referred toas dedicated signaling) to a given terminal apparatus 2A. In otherwords, user equipment specific (user equipment unique) information istransmitted by using the message dedicated to the certain terminalapparatus, PDSCH is used to transmit MAC CE.

Here, the RRC message and/o CE is also referred to as higher layersignaling.

The PDSCH can be used to request downlink channel state information. ThePDSCH can be used for transmission of an uplink resource to which a CSIfeedback report is mapped, the CSI feedback report being fed back to thebase station apparatus by the terminal apparatus. For example, the CSIfeedback report can be used for a configuration for indicating an uplinkresource that periodically reports Channel State Information (PeriodicCSI). The CSI feedback report can be used for a mode configuration (CSIreport mode) for periodically reporting the Channel State Information.

The type of the downlink Channel State Information report includeswideband CSI (e.g., Wideband CSI) and narrowband CSI (e.g., SubbandCSI). The wideband CSI calculates one piece of Channel State Informationfor the system band of a cell. The narrowband CSI divides the systemhand in prescribed units, and calculates one piece of Channel StateInformation for each division.

In the downlink radio communication, a Synchronization signal (SS) and aDownlink Reference Signal (DL RS) are used as downlink physical signals.The downlink physical signals are not used for transmission ofinformation output from the higher layers, but are used by the physicallayer. Note that the synchronization signal includes a PrimarySynchronization Signal (PSS) and a Secondary Synchronization Signal(SSS).

The synchronization signal is used for the terminal apparatus to takesynchronization in the frequency domain and the time domain in thedownlink. The synchronization signal is used to measure received power,received quality, or Signal-to-interference and Noise power Ratio(SINR). Note that the received power measured by the synchronizationsignal is also referred to as a Synchronization Signal-Reference SignalReceived Power (SS-RSRP), the received quality measured by thesynchronization signal is also referred to as a Reference SignalReceived Quality (SS-RSRQ), and an SINR measured by the synchronizationsignal is also referred to as an SS-SINR. Note that the SS-RSRQ is aratio between the SS-RSRP and the RSSI. The Received Signal StrengthIndicator (RSSI) is the total average received power for a certainobservation period. The synchronization signal/downlink reference signalis used for the terminal apparatus to perform channel compensation on adownlink physical channel. For example, the synchronizationsignal/downlink reference signal is used for the terminal apparatus tocalculate the downlink Channel State information.

Here, the downlink reference signal includes a Demodulation ReferenceSignal (DMRS), a Non-Zero Power Channel State Information-ReferenceSignal (NZP CSI-RS), a Zero Power Channel State Information-ReferenceSignal (ZP CSI-RS), a PT-RS, and a Tracking Reference Signal (TRS), Notethat a DMRS of the downlink is also referred to as a downlink DMRS. Notethat in the following embodiments, the NZP CSI-RS and/or the ZP CSI-RSare included in a case of simply referring to CSI-RS.

The DMRS is transmitted in a subframe and a band that are used fortransmission of PDSCH/PBCH/PDCCH/EPDCCH related to DMRS, and is used todemodulate PDSCH/PBCH/PDCCH/EPDCCH related to DMRS.

A resource for NZP CSI-RS is configured by the base station apparatus1A, For example, the terminal apparatus 2A performs signal measurement(channel measurement) or interference measurement by using the NZPCSI-RS. The NZP CSI-RS is also used for beam scanning for searching apreferable beam direction, beam recovery for recovering in a case of thereceived power/received quality in the beam direction deteriorates, orthe like. A resource for ZP CSI-RS is configured by the base stationapparatus 1A. With zero output, the base station apparatus IA transmitsZP CSI-RS. The terminal apparatus 2A performs interference measurementin a resource to which ZP CSI-RS corresponds, for example. Note that theresource for interference measurement corresponding to the ZP CSI-RS isalso referred to as a CSI-Interference Measurement (IM) resource.

The base station apparatus IA transmits (configures) the NZP CSI-RSresource configuration for the resource of the NZP CSI-RS. The NZPCSI-RS resource configuration includes some or all of one or more NZPCSI-RS resource mappings, a CSI-RS resource ID of each NZP CSI-RSresource, and the number of antenna ports. The CSI-RS resource mappingis information indicating an OFDM symbol and a subcarrier (e.g., aresource element) in a slot in which the CSI-RS resource is allocated.The CSI-RS resource ID is used to identify the NZP CSI-RS resource.

The base station apparatus 1A transmits (configures) the CSI-IM resourceconfiguration. The CSI-IM resource configuration includes one or moreCSI-IM resource mappings, and a CSI-IM resource configuration ID foreach CSI-IM resource. The CSI-IM resource mapping is informationindicating an OFDM symbol and a subcarrier (e.g., a resource element) ina slot in which the CSI-IM resource is allocated. The CSI-IM resourceconfiguration ID is used to identify the CSI-IM configuration resource.

The CSI-RS is used to measure received power, received quality, or SINR.The received power measured by the CSI-RS is referred to as a CSI-RSRP,the received quality measured by the CSI-RS is referred to as aCSI-RSRQ, and the SINR measured by the CSI-RS is also referred to as aCSI-SINR. Note that the CSI-RSRQ is a ratio between the CSI-RSRP and theRSSI.

The CSI-RS is transmittedperiodically/non-periodically/semi-persistently.

The terminal apparatus is configured with a higher layer with respect toCSI. For example, the terminal apparatus is configured with a CSI reportconfiguration that is a configuration of the CSI report, a CSI resourceconfiguration that is a configuration of the resource for measuring theCSI, and a measurement link configuration for linking the CSI reportconfiguration and the CSI resource configuration for the CSImeasurement. One or more of report configurations, resourceconfigurations, and measurement link configurations are configured.

The CSI report configuration includes some or all of a reportconfiguration ID, a report configuration type, a codebook configuration,a LSI report amount, and a block error rate target. The reportconfiguration ID is used to identify the CSI report configuration. Thereport configuration type indicates aperiodic/non-periodic/semi-persistent CSI report. The CSI report amountindicates the reported amount (value, type), for example, some or all ofCRI, RI, PMI, CQI, or RSRP. The block error rate target is a target ofblock error rate that is assumed in a case of computing the CQI.

The CSI resource configuration includes some or all of a resourceconfiguration ID, a synchronization signal block resource measurementlist, a resource configuration type, or one or more resource setconfigurations. The resource configuration ID is used to identify aresource configuration. The synchronization signal block resourceconfiguration list is a list of resources for which measurements aremade using synchronization signals. The resource configuration typeindicates whether the CSI-RS is transmitted periodically,non-periodically, or semi-persistently. Note that in the case of aconfiguration in which the CSI-RS is transmitted semi-persistently, theCSI-RS is periodically transmitted during a period since activated withhigher layer signaling or downlink control information untildeactivated.

The CSI-RS resource set configuration includes some or all of a CSI-RSresource set configuration ID, resource repetition, and informationindicating one or more CSI-RS resources. The resource set configurationID is used to identify the CSI-RS resource set configuration. Theresource repetition indicates the on/off of resource repetition withinthe resource set. In a case that the resource repetition is on, it meansthat the base station apparatus uses a fixed (identical) transmit beamin each of multiple CSI-RS resources in the resource set. In otherwords, in a case that the resource repetition is on, the terminalapparatus assumes that the base station apparatus is using a fixed(identical) transmit beam in each of multiple CSI-RS resources in theresource set. In a case that the resource repetition is off, it meansthat the base station apparatus does not use a fixed (identical)transmit beam on each of multiple CSI-RS resources in the resource set.In other words, in a case that the resource repetition is off, theterminal apparatus assumes that the base station apparatus is not usinga fixed (identical) transmit beam on each of multiple CSI-RS resourcesin the resource set. The information indicating the CSI-RS resourceincludes one or more CSI-RS resource IDs, and one or more CSI-IMresource configuration IDs.

The measurement link configuration includes some or all of themeasurement link configuration ID, the report configuration ID, and theresource configuration ID, and the CSI report configuration and the CSIresource configuration are linked with each other. The measurement linkconfiguration ID is used to identify the measurement link configuration.

The PT-RS is associated with the DMRS (DMRS port group). The number ofantenna ports of the PT-RS is one or two, and each PT-RS port (PT-RSantenna port) is associated with a DMRS port group (LAIRS antenna portgroup). The terminal apparatus assumes that the PT-RS port and the DMRSport (DMRS antenna port) are in QCL, for delay spread, Doppler spread,Doppler shift, average delay, and spatial reception (Rx) parameters. Thebase station apparatus configures the PT-RS configuration with higherlayer signaling. In a case that the PT-RS configuration is configured,the PT-RS can be transmitted. The PT-RS is not transmitted in a case ofa prescribed MCS (e.g., in a case that the modulation scheme is QPSK).The PT-RS configuration is configured with a time density and afrequency density. The time density indicates the time interval at whichthe PT-RS is allocated. The time density is indicated as a function ofthe scheduled MCS. The time density includes no PT-RS present (nottransmitted). The frequency density indicates the frequency interval atwhich the PT-RS is allocated. The frequency density is indicated as afunction of the scheduled bandwidth. The frequency density includes noPT-RS present (not transmitted). Note that in a case that the timedensity or the frequency density indicates that no PT-RS is present (nottransmitted), no PT-RS is present (transmitted).

Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN)

The RS is transmitted in the entire band of a subframe used fortransmission of a PMCH. An MBSFN RS is used to demodulate the PMCH. ThePMCH is transmitted through the antenna port used for transmission ofthe MBSFN RS.

Here, the downlink physical channel and the downlink physical signal arealso collectively referred to as a downlink signal. The uplink physicalchannel and the uplink physical signal are also collectively referred toas an uplink signal. The downlink physical channel and the uplinkphysical channel are also collectively referred to as a physicalchannel. The downlink physical signal and the uplink physical signal arealso collectively referred to as a physical signal.

The BCH, UL-SCH, and DL-SCH are transport channels. Channels used in theMedium Access Control (MAC) layer are referred to as transport channels.A unit of the transport channel used in the MAC layer is also referredto as a Transport Block (TB) or a MAC Protocol Data Unit (PDU). Thetransport block is a unit of data that the MAC layer delivers to thephysical layer. In the physical layer, the transport block is mapped toa codeword, and coding processing and the like are performed for eachcodeword.

For terminal apparatuses that supports Carrier Aggregation (CA), thebase station apparatus can integrate multiple Component Carriers (CCs)for transmission in a broader band to perform communication. In carrieraggregation, one Primary Cell (PCell) and one or more Secondary Cells(SCells) are configured as a set of serving cells,

In Dual Connectivity (DC), a Master Cell Group (MCG) and a SecondaryCell Group (SCG) are configured as a group of serving cells. The MCGincludes a PCell and optionally one or more SCells. The SCG includes aprimary SCell (PSCell) and optionally one or more SCells.

The base station apparatus can communicate by using a radio frame. Theradio frame includes multiple subframes (sub-periods). In a case that aframe length is expressed in time, for example, a radio frame length canbe 10 milliseconds (ms), and a subframe length can be 1 ms. In thisexample, the radio frame includes 10 subframes.

The slot includes 14 OFDM symbols. Since an OFDM symbol length may varydepending on a subcarrier spacing, the slot length may also varydepending on the subcarrier spacing. The mini-slot includes OFDM symbolsfewer than the slots. The slot/mini-slot can be used as a schedulingunit. Note that the terminal apparatus may recognize the position(mapping) of the first downlink DMRS in slot based scheduling/mini-slotbased scheduling. In the slot based scheduling, the first downlink DMRSis mapped to the third or fourth symbol of the slot. In the mini-slotbased scheduling, the first downlink DMRS is mapped to the first symbolof the scheduled data (resource, PDSCH). Note that the slot basedscheduling is also referred to as PDSCH mapping type A. The mini-slotbased scheduling is also referred to as PDSCH mapping type B.

The resource block is defined by 12 continuous subcarriers. The resourceelement is defined by an index of the frequency domain (e.g., asubcarrier index) and an index of the time domain (e.g., OFDM symbolindex). The resource element is classified as an uplink resourceelement, a downlink element, a flexible resource element, and a reservedresource element. In the reserved resource element, the terminalapparatus does not transmit an uplink signal and does not receive adownlink signal.

Multiple Subcarrier spacings (SCSs) are supported. For example, the SCSis 15/30/60/120/240/480 kHz.

The base station apparatus/terminal apparatus can communicate in alicensed band or an unlicensed band. The base station apparatus/terminalapparatus can perform carrier aggregation communication in which thelicensed band serves as the PCell and at least one SCell operates in anunlicensed band. The base station apparatus/terminal apparatus cancommunicate in dual connectivity in which the master cell groupcommunicates with the licensed band and the secondary cell groupcommunicates in the unlicensed band. The base station apparatus/terminalapparatus can communicate only with the PCell in the unlicensed band.The base station apparatus/terminal apparatus can communicate with CA orDC only in the unlicensed band. Note that communication in which thelicensed band serves as the PCell and a cell in the unlicensed band(SCell, PSCell) is assisted by, for example, CA, DC, or the like, isalso referred to as Licensed-Assisted Access (LAA). The communication ofthe base station apparatus/terminal apparatus only in the unlicensedband is also referred to as Unlicensed-standalone access (ULSA). Thecommunication of the base station apparatus/terminal apparatus only inthe licensed band is also referred to as Licensed Access (LA).

FIG. 2 is a schematic block diagram illustrating a configuration of thebase station apparatus according to the present embodiment. Asillustrated in FIG. 2, the base station apparatus includes a higherlayer processing unit (higher layer processing step) 101, a controller(controlling step) 102, a transmitter (transmitting step) 103, areceiver (receiving step) 104, a transmit and/or receive antenna 105,and a. measurement unit (measurement step) 106. The higher layerprocessing unit 101 includes a radio resource control unit (radioresource controlling step) 1011 and a scheduling unit (scheduling step)1012. The transmitter 103 includes a coding unit (coding step) 1031, amodulation unit (modulating step) 1032, a downlink reference signalgeneration unit (downlink reference signal generating step) 1033, amultiplexing unit (multiplexing step) 1034, and a radio transmittingunit (radio transmitting step) 1035. The receiver 104 includes a radioreceiving unit (radio receiving step) 1041, a demultiplexing unit(demultiplexing step) 1042, a demodulation unit (demodulating step)1043, and a decoding unit (decoding step) 1044.

The higher layer processing unit 101 performs processing of a MediumAccess Control (MAC) layer, a Packet Data Convergence Protocol (PDCP)layer, a Radio Link Control (RIX) layer, and a Radio Resource Control(RRC) layer. The higher layer processing unit 101 generates informationnecessary for control of the transmitter 103 and the receiver 104, andoutputs the generated information to the controller 102.

The higher layer processing unit 101 receives information of a terminalapparatus, such as a capability of the terminal apparatus (UEcapability), from the terminal apparatus. To rephrase, the terminalapparatus transmits its function to the base station apparatus by higherlayer signaling.

Note that in the following description, information of a terminalapparatus includes information for indicating whether the terminalapparatus supports a prescribed function, or information for indicatingthat the terminal apparatus has completed the introduction and test of aprescribed function. In the following description, information ofwhether the prescribed function is supported includes information ofwhether the introduction and test of the prescribed function have beencompleted.

For example, in a case that a terminal apparatus supports a prescribedfunction, the terminal apparatus transmits information (parameters) forindicating whether the prescribed function is supported. In a case thata terminal apparatus does not support a prescribed function, theterminal apparatus does not transmit information (parameters) forindicating whether the prescribed function is supported. In other words,whether the prescribed function is supported is notified by whetherinformation (parameters) for indicating whether the prescribed functionis supported is transmitted. The information (parameters) for indicatingwhether the prescribed function is supported may be notified by usingone bit of 1 or 0.

The radio resource control unit 1011 generates, or acquires from ahigher node, the downlink data (the transport block) allocated in thedownlink PDSCH, system information, the RRC message, the MAC ControlElement (CE), and the like. The radio resource control unit 1011 outputsthe downlink data to the transmitter 103, and outputs other informationto the controller 102. The radio resource control unit 1011 managesvarious configuration information of the terminal apparatuses.

The scheduling unit 1012 determines a frequency and a subframe to whichthe physical channels (PDSCH and PUSCH) are allocated, the coding rateand modulation scheme (or MCS) for the physical channels (PDSCH andPUSCH), the transmit power, and the like. The scheduling unit 1012outputs the determined information to the controller 102.

The scheduling unit 1012 generates information to be used for schedulingthe physical channels (PDSCH and PUSCH), based on the result of thescheduling. The scheduling unit 1012 outputs the generated informationto the controller 102.

Based on the information input from the higher layer processing unit101, the controller 102 generates a control signal for controlling thetransmitter 103 and the receiver 104. The controller 102 generates thedownlink control information based on the information input from thehigher layer processing unit 101, and outputs the generated informationto the transmitter 103.

The transmitter 103 generates the downlink reference signal inaccordance with the control signal input from the controller 102, codesand modulates the HARQ indicator, the downlink control information, andthe downlink data that are input from the higher layer processing unit101, multiplexes PHICH, PDCCH, EPDCCH, PDSCH, and the downlink referencesignal, and transmits a signal obtained through the multiplexing to theterminal apparatus 2A through the transmit and/or receive antenna 105.

The coding unit 1031 codes the HARQ indicator, the downlink controlinformation, and the downlink data that are input from the higher layerprocessing unit 101, in compliance with a predetermined coding scheme,such as block coding, convolutional coding, turbo coding, Low densityparity check (LDPC) coding, and Polar coding, or in compliance with acoding scheme determined by the radio resource control unit 1011. Themodulation unit 1032 modulates the coded bits input from the coding unit1031, in compliance with the modulation scheme prescribed in advance,such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying(QPSK), quadrature amplitude modulation (16 QAM), 64 QAM, or 256 QAM, orin compliance with the modulation scheme determined by the radioresource control unit 1011.

The downlink reference signal generation unit 1033 generates, as thedownlink reference signal, a sequence, known to the terminal apparatus2A, that is determined in accordance with a rule predetermined based onthe physical cell identity (PCI, cell ID) for identifying the basestation apparatus 1A, and the like.

The multiplexing unit 1034 multiplexes the modulated modulation symbolof each channel, the generated downlink reference signal, and thedownlink control information. To be more specific, the multiplexing unit1034 maps the modulated modulation symbol of each channel, the generateddownlink reference signal, and the downlink control information to theresource elements.

The radio transmitting unit 1035 performs Inverse Fast Fourier Transform(IFFT) on the modulation symbol resulting from the multiplexing or thelike, generates an OFDM symbol, adds a cyclic prefix (CP) to thegenerated OFDM symbol, generates a baseband digital signal, converts thebaseband digital signal into an analog signal, removes unnecessaryfrequency components through filtering, up-converts a result of theremoval into a signal of a carrier frequency, performs poweramplification, and outputs a final result to the transmit and/or receiveantenna 105 for transmission.

In accordance with the control signal input from the controller 102, thereceiver 104 demultiplexes, demodulates, and decodes the receptionsignal received from the terminal apparatus 2A through the transmitand/or receive antenna 105, and outputs information resulting from thedecoding to the higher layer processing unit 101.

The radio receiving unit 1041 converts, by down-converting, an uplinksignal received through the transmit and/or receive antenna 105 into abaseband signal, removes unnecessary frequency components, controls theamplification level in such a manner as to suitably maintain a signallevel, performs orthogonal demodulation based on an in-phase componentand an orthogonal component of the received signal, and converts theresulting orthogonally-demodulated analog signal into a digital signal.

The radio receiving unit 1041 removes a portion corresponding to CP fromthe digital signal resulting from the conversion. The radio receivingunit 1041 performs Fast Fourier Transform (FFT) of the signal from whichthe CP has been removed, extracts a signal in the frequency domain, andoutputs the resulting signal to the demultiplexing unit 1042.

The demultiplexing unit 1042 demultiplexes the signal input from theradio receiving unit 1041 into signals such as PUCCH, PUSCH, and uplinkreference signal. The demultiplexing is performed based on radioresource allocation information, included in the uplink grant notifiedto each of the terminal apparatuses 2A, that is predetermined by thebase station apparatus 1A by using the radio resource control unit 1011.

The demultiplexing unit 1042 performs channel compensation for PUCCH andPUSCH. The demultiplexing unit 1042 demultiplexes the uplink referencesignal.

The demodulation unit 1043 performs Inverse Discrete Fourier Transform(IDFT) of PUSCH, acquires modulation symbols, and demodulates, for eachof the modulation symbols of PUCCH and PUSCH, a reception signal incompliance with a predetermined modulation scheme, such as BPSK, QPSK,16 QAM, 64 QAM, and 256 QAM, or in compliance with a modulation schemethat the base station apparatus 1A notified to the terminal apparatuses2A in advance by using the uplink grant.

The decoding unit 1044 decodes the coded bits of PUCCH and PUSCH thathave been demodulated, at a coding rate, in compliance with apredetermined coding scheme, that is predetermined or notified from thebase station apparatus 1A to the terminal apparatus 2A in advance byusing the uplink grant, and outputs the decoded uplink data and uplinkcontrol information to the higher layer processing unit 101. In a casethat PUSCH is retransmitted, the decoding unit 1044 performs thedecoding by using the coded bits that is input from the higher layerprocessing unit 101 and retained in an HARQ buffer, and the demodulatedcoded bits.

The measurement unit 106 observes the reception signal, and determinesvarious measurement values such as RSRP/RSRQ/RSSI. The measurement unit106 determines the received power, the received quality, and apreferable SRS resource index from the SRS transmitted from the terminalapparatus.

FIG. 3 is a schematic block diagram illustrating a configuration of theterminal apparatus according to the present embodiment. As illustratedin FIG. 3, the terminal apparatus includes a higher layer processingunit (higher layer processing step) 201, a controller (controlling step)202, a transmitter (transmitting step) 203, a receiver (receiving step)204, a measurement unit (measurement step) 205, and a transmit and/orreceive antenna 206. The higher layer processing unit 201 includes aradio resource control unit (radio resource controlling stop) 2011 and ascheduling information interpretation unit (scheduling informationinterpreting step) 2012. The transmitter 203 includes a coding unit(coding step) 2031, a modulation unit (modulating step) 2032, an uplinkreference signal generation unit (uplink reference signal generatingstep) 2033, a multiplexing unit (multiplexing step) 2034, and a radiotransmitting unit (radio transmitting step) 2035. The receiver 204includes a radio receiving unit (radio receiving step) 2041, ademultiplexing unit (demultiplexing step) 2042, and a signal detectionunit (signal detecting step) 2043.

The higher layer processing unit 201 outputs, to the transmitter 203,the uplink data (the transport block) generated by a user operation orthe like. The higher layer processing unit 201 performs processing ofthe Medium Access Control (MAC) layer, the Packet Data ConvergenceProtocol (PDCP) layer, the Radio Link Control (RLC) layer, and the RadioResource Control (RRC) layer.

The higher layer processing unit 201 outputs, to the transmitter 203,information for indicating a terminal apparatus function supported bythe terminal apparatus 2A.

Furthermore, the radio resource control unit 2011 manages variousconfiguration information of the terminal apparatuses 2A. The radioresource control unit 2011 generates information to be mapped to eachuplink channel, and outputs the generated information to the transmitter203.

The radio resource control unit 2011 acquires configuration informationtransmitted from the base station apparatus, and outputs the acquiredinformation to the controller 202.

The scheduling information interpretation unit 2012 interprets thedownlink control information received through the receiver 204, anddetermines scheduling information. The scheduling informationinterpretation unit 2012 generates control information in order tocontrol the receiver 204 and the transmitter 203 in accordance with thescheduling information, and outputs the generated information to thecontroller 202.

Based on the information input from the higher layer processing unit201, the controller 202 generates a control signal for controlling thereceiver 204, the measurement unit 205, and the transmitter 203. Thecontroller 202 outputs the generated control signal to the receiver 204,the measurement unit 205, and the transmitter 203 to control thereceiver 204 and the transmitter 203.

The controller 202 controls the transmitter 203 so as to transmit theCSI/RSRP/RSRQ/RSSI generated by the measurement unit 205 to the basestation apparatus.

In accordance with the control signal input from the controller 202, thereceiver 204 demuitiplexes, demodulates, and decodes a reception signalreceived from the base station apparatus through the transmit and/orreceive antenna 206, and outputs the resulting information to the higherlayer processing unit 201.

The radio receiving unit 2041 converts, by down-converting, a downlinksignal received through the transmit and/or receive antenna 206 into abaseband signal, removes unnecessary frequency components, controls theamplification level in such a manner as to suitably maintain a signallevel, performs orthogonal demodulation based on an in-phase componentand an orthogonal component of the received signal, and converts theresulting orthogonally-demodulated analog signal into a digital signal.

The radio receiving unit 2041 removes a portion corresponding to CP fromthe digital signal resulting from the conversion, performs fast Fouriertransform of the signal from which the CP has been removed, and extractsa signal in the frequency domain.

The demultiplexing unit 2042 demuitiplexes the extracted signal intoPHICH, PUCCH, EPDCCH, PDSCH, and the downlink reference signal. Thedemultiplexing unit 2042 performs channel compensation for PHICH, PDCCH,and EPDCCH based on a channel estimation value of a desired signalobtained from channel measurement, detects downlink control information,and outputs the detected downlink control information to the controller202. The controller 202 outputs PDSCH and the channel estimation valueof the desired signal to the signal detection unit 2043.

The signal detection unit 2043, by using PDSCH and the channelestimation value, performs demodulation and decoding, and outputs thedemodulated and decoded signal to the higher layer processing unit 201.In a case that the signal detection unit 2043 cancels or suppresses theinterference signal, the signal detection unit 2043 acquires the channelestimation value of the interference channel by using the parameter ofthe interference signal, and demodulates and decodes the PDSCH.

The measurement unit 205 performs various measurements such as a CSImeasurement, a Radio Resource Management (RRM) measurement, a Radio LinkMonitoring (RLM) measurement, and the like, and determines theCSI/RSRP/RSRQ/RSSI, and the like.

The transmitter 203 generates an uplink reference signal in accordancewith the control signal input from the controller 202, codes andmodulates the uplink data (the transport block) input from the higherlayer processing unit 201, multiplexes PUCCH, PUSCH, and the generateduplink reference signal, and transmits a signal resulting from themultiplexing to the base station apparatus through the transmit and/orreceive antenna 206.

The coding unit 2031 codes the uplink control information or uplink datainput from the higher layer processing unit 201 in compliance withconvolutional coding, block coding, turbo coding, LDPC coding, Polarcoding, or the like.

The modulation unit 2032 modulates the coded bits input from the codingunit 2031, in compliance with a modulation scheme, such as BPSK, QPSK,16 QAM, or 64 QAM, that is notified by using the downlink controlinformation, or in compliance with a modulation scheme predetermined foreach channel.

The uplink reference signal generation unit 2033 generates a sequencethat is determined according to a predetermined rule (formula), based ona physical cell identity (PCI, also referred to as a Cell ID or thelike) for identifying the base station apparatus, a bandwidth in whichthe uplink reference signal is mapped, a cyclic shift notified by usingthe uplink grant, a parameter value for generation of a DMRS sequence,and the like.

The multiplexing unit 2034 multiplexes PUCCH and PUSCH signals and thegenerated uplink reference signal for each transmit antenna port. To bemore specific, the multiplexing unit 2034 maps the PUCCH and PUSCHsignals and the generated uplink reference signal to resource elementsfor each transmit antenna port.

The radio transmitting unit 2035 performs Inverse Fast Fourier Transform(IFFT) on a signal resulting from the multiplexing, performs themodulation of OFDM scheme, generates an OFDMA symbol, adds CP to thegenerated OFDMA symbol, generates a baseband digital signal, convertsthe baseband digital signal into an analog signal, removes unnecessaryfrequency components, up-converts a result of the removal into a signalof a carrier frequency, performs power amplification, and outputs afinal result to the transmit and/or receive antenna 206 fortransmission.

Note that the terminal apparatus can perform modulation according to notonly an OFDMA scheme but also an SC-FDMA scheme.

As a technique for increasing system throughput, multi-user MultipleInput Multiple Output (MIMO) transmission that spatially multiplexesmultiple terminal apparatuses are effective. FIG. 4 is a diagramillustrating an example of a communication system according to thepresent embodiment. The communication system illustrated in FIG. 4includes a base station apparatus 3A and terminal apparatuses 4A and 4B.In a case that the base station apparatus 3A perform multi-user MIMOtransmission to the terminal apparatuses 4A and 4B, performancedegradation may be caused due to inter-user interference. Note that theterminal apparatuses 4A and 4B are also simply referred to as terminalapparatuses.

In a case that ultra-large capacity communication is required, such asultra-high definition video transmission, ultra-wideband transmissionutilizing high frequency bands is desired. Transmission in the highfrequency bands needs to compensate for pathloss and beamforming isimportant. In an environment in which multiple terminal apparatuses arepresent in a limited area, an Ultra-dense network with a high density ofbase station apparatuses located is effective in a case that ultra-largecapacity communication is required for each terminal apparatus. However,in a case that the base station apparatuses are located in high density,the Signal to noise power ratio (SNR) greatly improves, but stronginterference due to beamforming may arrive. Accordingly, in order torealize ultra-large capacity communication for every terminal apparatusin the limited area, interference control (avoidance, suppression,cancellation) in consideration of beamforming, and/or coordinatedcommunication of multiple base stations are necessary.

FIG. 5 is a diagram illustrating an example of a communication system ofthe downlink according to the present embodiment. The communicationsystem illustrated in FIG. 5 includes a base station apparatus 3A, abase station apparatus 5A, and a terminal apparatus 4A. The terminalapparatus 4A can use the base station apparatus 3A and/or the basestation apparatus 5A as a serving cell. In a case that the base stationapparatus 3A or the base station apparatus 5A is provided with a numberof antennas, a number of antennas can be divided into multiple subarrays(panels, sub-panels, transmit antenna ports, transmit antenna groups,receive antenna ports, receive antenna groups, antenna groups, andantenna. port groups), and transmit/receive beamforming may be appliedfor each subarray. In this case, each subarray may include acommunication apparatus, and the configuration of the communicationapparatus is the same as the base station apparatus configurationillustrated in FIG. 2, unless otherwise indicated. In a case that theterminal apparatus 4A includes multiple antennas, the terminal apparatus4A can transmit or receive by beamforming. In a case that the terminalapparatus 4A is provided with a number of antennas, a number of antennascan be divided into multiple subarrays (panels, sub-panels, transmitantenna. ports, transmit antenna groups, receive antenna ports, receiveantenna groups, antenna groups, and antenna port groups), and differenttransmit/receive beamforming may be applied for each subarray. Eachsubarray may include a communication apparatus, and the configuration ofthe communication apparatus is the same as the terminal apparatusconfiguration illustrated in FIG. 3 unless otherwise indicated. Notethat the base station apparatus 3A and the base station apparatus 5A arealso simply referred to as base station apparatuses. Note that theterminal apparatus 4A is also simply referred to as a terminalapparatus.

A synchronization signal is used to determine a preferable transmit beamof the base station apparatus, and a preferable receive beam for theterminal apparatus. The base station apparatus transmits synchronizationsignal blocks including the PSS, PBCH, and SSS. Note that, in asynchronization signal block burst set period configured by the basestation apparatus, one or more synchronization signal blocks aretransmitted in the time domain, and a time index is configured for eachsynchronization signal block. The terminal apparatus may consider thatsynchronization signal blocks with the same time index within asynchronization signal block burst set period are transmitted fromalmost the same location (quasi co-location (QCL)) such that the delayspread, Doppler spread, Doppler shift, average gain, average delay,spatial reception parameters, and/or spatial transmission parameters canbe considered to be the same. Note that examples of the spatialreception parameters (Rx parameter, reception filter) include a spatialcorrelation of the channels, Angle of Arrival, and the receive beamdirection. Examples of the spatial transmission parameters include aspatial correlation of the channels, Angle of Departure, and thetransmit beam direction. In other words, the terminal apparatus canassume that synchronization signal blocks of the same time index whilingthe synchronization signal block burst set period are transmitted withthe same transmit beam, and that synchronization signal blocks ofdifferent time indexes have been transmitted with different beams.Accordingly, in a case that the terminal apparatus reports, to the basestation apparatus, information indicating a time index of a preferablesynchronization signal block in the synchronization signal block burstset period, the base station apparatus can recognize a transmit beampreferable for the terminal apparatus. The terminal apparatus candetermine a receive beam preferable for the terminal apparatus by usingsynchronization signal blocks of the same time index in differentsynchronization signal block burst set periods. Thus, the terminalapparatus can associate the time index of the synchronization signalblocks with the receive beam direction and/or subarray. Note that, in acase that the terminal apparatus includes multiple subarrays andconnects with different cells, different subarrays may be used. Notethat the time index of the synchronization signal block is also referredto as an SSB index or an SSB Resource Indicator (SSBRI).

There are also four QCL types indicative of the state of QCL. The fourQCL types are referred to as QCL type A, QCL type B, QCL type C, and QCLtype The QCL, type A is a relationship (state) where Doppler shift,Doppler spread, average delay, and delay spread are QCL. The QCL type Bis a relationship (state) where Doppler shift and Doppler spread areQCL. The QCL type C is a relationship (state) where average delay andDoppler shift are QCL. The QCL type D is a relationship (state) in whichthe spatial reception parameters are QCL. Note that each of the four QCLtypes can be combined. For example, there may be QCL type A+QCL type D,QCL type B+QCL type D, and the like.

One or more Transmit Configuration Indicator (TCI) states are configuredby higher layer signaling. One TCI state can configure the QCL type forone or more downlink signals in a certain cell (cell ID) in a certainbandwidth part (BWP-ID). The downlink signal includes a CSI-RS and SSB.Note that the TCI state is configured by an RRC message (signaling), andone or more of the configured TCI states are activated/deactivated inthe MAC layer. The TCI state can be associated with the QCL between thedownlink signal and the DMRS of the PDSCH. For example, one or more ofthe TCI states activated by the DCI may be indicated and used todemodulate (decode) the associated PDSCH. Note that in a case that theQCL type D is configured for the TCI state received in the DCI, theterminal apparatus can recognize the receive beam direction (spatialreception filter) of the associated PDSCH. Therefore, the TCI can besaid to be information related to the receive beam direction of theterminal apparatus. The TCI state can be associated with the QCL betweenthe downlink signal and the DMRS of the PDCCH. From the one or more TCIstates configured by the RRC message (signaling), one TCI state isactivated as a TCI state for the PDCCH in the MAC layer. As a result,the terminal apparatus can recognize the receive beam direction of thePDCCH DMRS. Note that a default receive beam direction of the PDCCH DMRSis associated with the SSB index at the time of initial access.

The CSI-RS can be used to determine a preferable transmit beam of thebase station apparatus and a preferable receive beam of the terminalapparatus.

The terminal apparatus receives the CSI-RS in the resource configured bythe CSI resource configuration, calculates the CSI or RSRP from theCSI-RS, and reports the CSI or RSRP to the base station apparatus. In acase that the CSI-RS resource configuration includes multiple CSI-RSresource configurations and/or the resource repetition is off, theterminal apparatus receives the CSI-RS in the same receive beam in eachCSI-RS resource and calculates the CRI. For example, in a case that theCSI-RS resource set configuration includes K (where K is an integer of 2or more) CSI-RS resource configurations, the CRI indicates N CSI-RSresources preferable from the K CSI-RS resources. Here, N is a positiveinteger less than K. In a case that the terminal apparatus reportsmultiple CRIs, the terminal apparatus can report the CSI-RSRP measuredby each CSI-RS resource to the base station apparatus in order toindicate which CSI-RS resource is good in quality. Transmitting, by thebase station apparatus, the CSI-RS by beamforming (preceding) indifferent beam directions in the multiple configured CSI-RS resources,allows for the base station apparatus to recognize the transmit beamdirection of the base station apparatus preferable for the terminalapparatus by the CRI reported from the terminal apparatus. Meanwhile,the preferable receive beam direction of the terminal apparatus can bedetermined by the transmit beam of the base station apparatus using afixed CSI-RS resource, For example, in a case that the CSI-RS resourceconfiguration includes multiple CSI-RS resource configurations and/orthe resource repetition is on, the terminal apparatus can determine apreferable receive beam direction from the CSI-RS received in eachdifferent receive beam direction in each CSI-RS resource. Note that theterminal apparatus may report the CSI-RSRP after determining apreferable receive beam direction. Note that in a case that the terminalapparatus includes multiple subarrays, the terminal apparatus can selecta preferable subarray in determining a preferable receive beamdirection. Note that a preferable receive beam direction of the terminalapparatus may be associated with a CRI (or CSI-RS resource ID). In acase that the terminal apparatus reports multiple CRIB, the base stationapparatus can fix the transmit beam with the CSI-RS resource associatedwith each CRI (or CSI-RS resource ID). At this time, the terminalapparatus can determine a preferable receive beam direction for each CRI(or CSI-RS resource ID). For example, the base station apparatus cantransmit a downlink signal/channel and a CRI (or CSI-RS resource ID) inassociation with each other. At this time, the terminal apparatus needsto receive a receive beam associated with the CRI. In the multipleCSI-RS resources configured, different base station apparatuses cantransmit the CSI-RS. In this case, it is possible for the network sideto recognize of which base station apparatus the communication qualityis good by the CRI (or CSI-RS resource ID). In a case that the terminalapparatus includes multiple subarrays, the terminal apparatus canreceive using the multiple subarrays at the same timing. Accordingly, ina case that the base station apparatus transmits the CRI (or CSI-RSresource ID) in association with each of multiple layers (codeword,transport block) by using downlink control information or the like, theterminal apparatus can receive at multiple layers by using a subarrayand a receive beam corresponding to each CRI (or CSI-RS resource ID).However, in a case that an analog beam is used, and one receive beamdirection is used at the same timing in one subarray, and in a case thattwo CRTs (or CSI-RS resource IDs) corresponding to one subarray of theterminal apparatus are simultaneously configured, the terminal apparatusmay fail to receive at multiple receive beams. To avoid this problem,for example, the base station apparatus groups the multiple CSI-RSresources configured, and the CRI is determined in a group by using thesame subarray. In a case that different subarrays are used betweengroups, the base station apparatus can recognize multiple CRIs that canbe configured at the same timing. Note that the CSI-RS resource groupmay be a CSI-RS resource configured with a CSI resource configuration ora CSI-RS resource set configuration. Note that the CRI (or CSI-RSresource ID) that can be configured at the same timing may be consideredto be QCL. At this time, the terminal apparatus can transmit the CRI (orCSI-RS resource ID) in association with the QCL information. The QCLinformation is information about QCL for a prescribed antenna port, aprescribed signal, or a prescribed channel. In a case that, in twoantenna ports, long term performance of a channel on which a symbol onOne antenna port is carried can be estimated from a channel on which asymbol on the other antenna port is carried, the two antenna ports aresaid to be quasi co-located (in a QCL state). The long term performanceincludes at least one of a delay spread, a Doppler spread, a Dopplershift, an average gain, an average delay, a spatial reception parameter,and/or a spatial transmission parameter. For example, in a case that twoantenna ports are quasi co-located (in a QCL state), the terminalapparatus can consider the two antenna ports to have the same long termperformance. For example, in a case that the terminal apparatus reportsCRI that is QCL for the spatial reception parameters and CRI that is notQCL for the spatial reception parameters in a distinguishing manner, thebase station apparatus is able to not to configure the CRI that is QCL,for the spatial reception parameters to the same timing, but configurethe CRI that is not QCL for the spatial reception parameters to the sametiming. The base station apparatus may request CSI for each subarray ofthe terminal apparatus. In this case, the terminal apparatus reports CSIfor each subarray. Note that, in a case that the terminal apparatusreports multiple CRIs to the base station apparatus, only CRI that isnot QCL may be reported.

In order to determine a preferable transmit beam of the base stationapparatus, a codebook is used in which candidates for a prescribedprecoding (beamforming) matrix (vector) are defined. The base stationapparatus transmits the CSI-RS, and the terminal apparatus determines apreferable precoding (beamforming) matrix from the codebook, and reportsthe matrix as PMI to the base station apparatus. Thereby, the basestation apparatus can recognize a preferable transmit beam direction forthe terminal apparatus. Note that the codebook includes precoding(beamforming) matrices for combining antenna ports and preceding (beamforming) matrices for selecting an antenna port. In a case of using acodebook for selecting the antenna port, the base station apparatus mayuse different transmit beam directions for antenna ports. Accordingly,in a case that the terminal apparatus reports a preferable antenna portas PMI, the base station apparatus can recognize a preferable transmitbeam direction. Note that a preferable receive beam of the terminalapparatus may be the receive beam direction associated with the CRI (orCSI-RS resource ID), or the terminal apparatus may determine apreferable receive beam direction again. In the case of using thecodebook for selecting the antenna port, and that a preferable receivebeam direction for the terminal apparatus is the receive beam directionassociated with the CRI (or CSI-RS resource ID), it is desirable thatthe receive beam direction for receiving the CSI-RS is the receive beamdirection associated with the CRI (or CSI-RS resource ID) to receive.Note that even in a case that the receive beam direction associated withthe CRI (or CSI-RS resource ID) is used, the terminal apparatus canassociate the PMI with the receive beam direction. In the case of usingthe codebook for selecting the antenna port, each antenna port may betransmitted from different base station apparatuses (cells). In thiscase, in a case that the terminal apparatus reports the PMI, the basestation apparatus can recognize with which base station apparatus (cell)communication quality is preferable. Note that in this case, the antennaports of different base station apparatuses (cells) may not be QCL.

In order to improve reliability and increase frequency efficiency,coordinated communication of multiple base station apparatuses(transmission and/or reception points) can be performed. The coordinatedcommunication of multiple base station apparatuses (transmission and/orreception points) include, for example, Dynamic Point Selection (DPS)for dynamically switching a preferable base station apparatus(transmission and/or reception point), Joint Transmission (JT), in whichthe same or different data signals are transmitted from multiple basestation apparatuses (transmission and/or reception points), and thelike. In a case that the same data is transmitted from multiple basestation apparatuses (transmission and/or reception points), reliabilitycan be improved, and in a case that different data is transmitted frommultiple base station apparatuses (transmission and/or receptionpoints), frequency efficiency and throughput can be improved. In a casethat the terminal apparatus communicates with multiple base stationapparatuses, the terminal apparatus may communicate by using multiplesubarrays. For example, in a case that the terminal apparatus 4Acommunicates with the base station apparatus 3A, the subarray 1 may beused, and in a case that the terminal apparatus 4A communicates with thebase station apparatus 5A, the subarray 2 may be used. In a case thatthe terminal apparatus is in coordinated communication with multiplebase station apparatuses, the terminal apparatus may dynamically switchmultiple subarrays or transmit and/or receive using multiple subarraysat the same timing. At this time, it is desirable that the terminalapparatus 4A and the base station apparatus 3A/5A share informationrelated to subarrays of the terminal apparatuses used for thecommunication.

The terminal apparatus can include CSI configuration information in theCSI report. For example, the CSI configuration information may includeinformation indicating a subarray. For example, the terminal apparatusmay transmit a CSI report including an index indicating CRI (or CSI-RSresource ID) and a subarray. In this way the base station apparatus canassociate the transmit beam direction with the subarray of the terminalapparatus. Alternatively, the terminal apparatus may transmit a CRIreport including multiple CRIs (or CSI-RS resource IDs). In this case,in a case that it is prescribed that some of the multiple CRIs (orCSI-RS resource IDs) are associated with the subarray 1 and the rest ofthe CRIs (or CSI-RS resource IDs) are associated with the subarray 2,the base station apparatus can associate the index indicating thesubarray with the CRI (or CSI-RS resource ID). The terminal apparatuscan perform joint coding on the CRI (or CSI-RS resource ID) and theindex indicating the subarray to transmit the CRI report in order toreduce the control information. In this case, of the N (N is an integerof 2 or more) bits indicating CRI, one bit indicates subarray 1 orsubarray 2, and the remaining bits indicate CRI. Note that, in a case ofjoint coding, one bit is used for an index indicating a subarray, so thenumber of bits that can represent the CRI is reduced. Thus, in a casethat the terminal apparatus reports the CSI report including an indexindicating a subarray, and that the number of CSI-RS resources indicatedby the CSI resource configuration is greater than the number capable ofrepresenting the CRI, the terminal apparatus can determine the CRI fromsome of CSI-RS resources. Note that in different CSI resourceconfigurations, in a case that the CSI is determined to be calculated indifferent subarrays, the base station apparatus can recognize the CSIfor each subarray of the terminal in a case that the terminal apparatustransmits CSI calculated by subarrays different for each resource.configuration ID.

The CSI configuration information can include configuration informationfor the CSI measurement. For example, the configuration information forthe CSI measurement may be a measurement link configuration or otherconfiguration information. As a result, the terminal apparatus canassociate the configuration information for the CSI measurement with thesubarray and/or the receive beam direction. For example, in a case ofconsidering coordinated communication with two base station apparatuses(e.g., base station apparatuses 3A and 5A), it is desirable that thereare several types of configuration information. Suppose that aconfiguration of the CSI-RS for channel measurement transmitted by thebase station apparatus 3A is set as resource configuration 1, and aconfiguration of the CSI-RS for channel measurement transmitted by thebase station apparatus 5A is set as resource configuration 2. In thiscase, the configuration information 1 may be the resource configuration1, the configuration information 2 may be the resource configuration 2,and the configuration information 3 may be the resource configuration 1and the resource configuration 2. Note that each of the configurationinformation may include a configuration of the interference measurementresource. In a case that the CSI measurement is performed based onconfiguration information 1, the terminal apparatus can measure CSI inthe CSI-RS transmitted from the base station apparatus 3A. In a casethat the CSI measurement is performed based on configuration information2, the terminal apparatus can measure the CSI transmitted from the basestation apparatus 5A. In a case that the CSI measurement is performedbased on configuration information 3, the terminal apparatus can measureCSI in the CSI-RS transmitted from the base station apparatus 3A and thebase station apparatus 5A. The terminal apparatus can associate thesubarray and/or the receive beam direction used for the CSI measurementwith respect to each of the configuration information 1 to 3.Accordingly, the base station apparatus can indicate a preferablesubarray and/or receive beam direction used by the terminal apparatus byindicating the configuration information 1 to 3. Note that in a casethat the configuration information 3 is configured, the terminalapparatus determines the CSI for the resource configuration 1 and/or CSIfor the resource configuration 2 At this time, the terminal apparatuscan associate the subarray and/or the receive beam direction for each ofthe resource configuration 1 and/or the resource configuration 2. It isalso possible to associate the resource configuration 1 and/or theresource configuration 2 with a codeword (transport block). For example,the CSI for the resource configuration 1 can be the CSI of a codeword 1(transport block 1), and the CSI for the resource configuration 2 can bethe CSI of a codeword 2 (transport block 2). The terminal apparatus candetermine one CSI in consideration of the resource configuration 1 andthe resource configuration 2. However, even in a case that one CSI isrequired, the terminal apparatus can associate the subarray and/or thereceive beam direction for each of the resource configuration 1 and theresource configuration 2.

In a case that multiple resource configurations are configured (forexample, in a case that the configuration information 3 described aboveis configured), the CSI configuration information may includeinformation indicating whether the CSI includes one CRI or includes CRIfor each of the multiple resource configurations. In a case that the CSIincludes one CM, the CSI configuration information may include aresource configuration ID by which CRI has been calculated. According tothe CSI configuration information, the base station apparatus canrecognize on which assumption the terminal apparatus has calculated CSIor of which resource configuration the received quality is good.

The base station apparatus can transmit a CSI request to request a CSIreport to the terminal apparatus. The CSI request can include reportingCSI for one subarray or reporting CSI for multiple subarrays. In thiscase, in a case that the terminal apparatus is required to report CSIfor one subarray, the terminal apparatus transmits a CSI report notincluding the index indicating the subarray. In a case that the CSI forthe multiple subarrays is required to be reported, the terminalapparatus transmits a CSI report including the indexes indicating thesubarrays. Note that, in a case that the base station apparatus requeststhe CSI report for one subarray, the base station apparatus can indicatethe subarray for which CSI is to be calculated by the terminalapparatus, by using an index or a resource configuration ID indicatingthe subarray. In this case, the terminal apparatus calculates the CSIfor the subarray indicated by the base station apparatus.

The base station apparatus can transmit a CSI request includingconfiguration information for the CSI measurement. In a case that theCSI request includes configuration information for the CSI measurement,the terminal apparatus determines the CSI based on the configurationinformation for the CSI measurement. The terminal apparatus may reportCSI to the base station apparatus, but may not report the configurationinformation for the CSI measurement.

The terminal apparatus and the base station apparatus according to thepresent embodiment can configure new virtual antenna ports in order toselect a preferable subarray. The virtual antenna ports are eachassociated with a physical subarray and/or a receive beam. The basestation apparatus can notify the terminal apparatus of the virtualantenna ports, and the terminal apparatus can select a subarray forreceiving the PDSCH. The virtual antenna ports can be configured withQCL. The base station apparatus can notify multiple terminal apparatusesof the virtual antenna ports. In a case that the notified virtualantenna ports are QCL, the terminal apparatus may receive the associatedPDSCH by using one subarray, and in a case that the notified virtualantenna ports are not QCL, the terminal apparatus may receive theassociated PDSCH by using two or more subarrays. The virtual antennaports can be associated with any one or more of a CSI-RS resource, aDMRS resource, and an SRS resource. By configuring the virtual antennaports, the base station apparatus can configure a subarray in a casethat the terminal apparatus transmits the RS with the resource in anyone or more of the CSI-RS resource, the DMRS resource, and the SRSresource.

In a case that multiple base station apparatuses performs coordinatedcommunication, it is desirable for the terminal apparatus to receiveusing the subarrays and/or receive beam directions preferable for thePDSCH transmitted by each base station apparatus. Thus, the base stationapparatus transmits information for the terminal apparatus to receiveusing a preferable subarray and/or receive beam direction. For example,the base station apparatus can transmit CSI configuration information orinformation indicating CSI configuration information in the downlinkcontrol information. In a case that the terminal apparatus receives theCSI configuration information, the terminal apparatus can receive usingthe subarray and/or the receive beam direction associated with the CSIconfiguration information.

For example, the base station apparatus can transmit informationindicating the subarray and/or the receive beam direction as the CSIconfiguration information. Note that the CSI configuration informationmay be transmitted in a prescribed DCI format. The informationindicating the receive beam direction may be the time index of the CRI(or CSI-RS resource ID), the PMI, or the synchronization signal block.The terminal apparatus can recognize the preferable subarray and/or thereceive beam direction from the received DCI. Note that the informationindicating the subarray is expressed as one bit or two bits. In a casethat the information indicating the subarray is indicated by one bit,the base station apparatus may indicate the subarray 1 or the subarray 2by “0” or “1” to the terminal apparatus. In a case that the informationindicating the subarray is indicated by two bits, the base stationapparatus may indicate the terminal apparatus to switch subarrays andreceive using two subarrays. Note that in different resourceconfigurations, in a case that the CSI is determined to be calculatedfor different subarrays, the base station apparatus can indicate thesubarray of the terminal apparatus by transmitting the DCI including theresource configuration ID.

For example, the base station apparatus can transmit configurationinformation for the CSI measurement as CSI configuration information. Inthis case, the terminal apparatus can receive the PDSCH using thesubarray and/or the receive beam direction associated with the CSI fedback by the configuration information of the received CSI measurement.Note that in a case that the configuration information for the CSImeasurement indicates the configuration information 1 or theconfiguration information 2, the CSI configuration information indicatesthat the PDSCH transmission is associated with one resourceconfiguration information. In a case that the configuration informationfor the CSI measurement indicates the configuration information 3, theCSI configuration information indicates that the PDSCH transmission isassociated with multiple pieces of resource configuration information.

The CSI configuration information may be associated with a parameter(field) included in the DCI, such as a DMRS Scrambling identity (SCID).For example, the base station apparatus can configure the association ofthe SCID and the configuration information for the CSI measurement. Inthis case, the terminal apparatus can refer to the configurationinformation for the CSI measurement from the SCID included in the DCI,and can receive the PDSCH using the subarray and/or the receive beamdirection associated with the configuration information for the CSImeasurement.

The base station apparatus can configure two DMRS antenna port groups.The two DMRS port groups are also referred to as DMRS port group 1(first DMRS port group), and DMRS port group 2 (second DMRS port group).The antenna ports in the DMRS antenna port group are QCL, and theantenna ports between the DMRS antenna port groups are not QCL.Accordingly, in a case that the DMRS antenna port group and the subarrayof the terminal apparatus are associated with each other, the basestation apparatus can indicate the subarray of the terminal apparatuswith the DMRS antenna port number included in the DCI. For example, in acase that the DMRS antenna port number included in the DCI is includedin one DMRS antenna port group, the terminal apparatus receives usingone subarray corresponding to the DMRS antenna port group. In a casethat the DMRS antenna port number included in the DCI is included inboth the two DMRS antenna port groups, the terminal apparatus receivesusing two subarrays. One DMRS antenna port group may be associated withone codeword (transport block). The relationship between the DMRSantenna port group and the index of the codeword (transport block) maybe predetermined or may be indicated by the base station apparatus.

Note that in different resource configurations, in a case that the CSIis determined to be calculated for different subarrays, and that theDMRS antenna port group is associated with the resource configuration IDor CSI-RS resource, by the DMRS antenna port included in the DCI, theterminal apparatus can identify the resource configuration ID or theCSI-RS resource, and can recognize the subarray and/or the receive beamdirection.

The base station apparatus can configure the DMRS antenna port group andCSI configuration information in association with each other. Note thatin a case that the CSI configuration information includes theconfiguration information for the CSI measurement and the configurationinformation for the CSI measurement indicates the configurationinformation 3, the terminal apparatus demodulates using the subarrayand/or receive beam direction corresponding to the resourceconfiguration 1 for the DMRS antenna port included in the DMRS antennaport group 1, and the terminal apparatus demodulates using the subarrayand/or receive beam direction corresponding to the resourceconfiguration 2 for the DMRS antenna port included in the DMRS antennaport group 2.

In a case that the report amount is configured to the CRI/RSRP orSSBRI/RSRP in the CSI report configuration, and that the group basedbeam reporting is configured to be off, the terminal apparatus reportsone, two, or four different CRIs or SSBRIs in one report. In a case thatthe report amount is configured to the CRI/RSRP or SSBRI/RSRP in the CSIreport configuration, and that the group based beam reporting isconfigured to be on, the terminal apparatus reports two different CRIsor SSBRIs in one report. However, the two CSI-RS resources or the twoSSB can be received simultaneously by one spatial domain receptionfilter or multiple spatial domain reception filters.

In a case that the report amount is configured to the CRI, RI, or CQI inthe CSI report configuration, and in a case that the group based beamreporting is configured to be on, the terminal apparatus determines theCSI based on two CSI-RS resources that can be received simultaneously byone spatial domain reception filter (panel, subarray) or multiplespatial domain reception filters (panels, subarrays). The two CSI-RSresources are referred to as a first CSI-RS resource and a second CSI-RSresource, respectively. The CRI indicating the first CSI-RS resource isalso referred to as a first CRI, and the CRI indicating the secondCSI-RS resource is also referred to as a second CRI, The RI determinedby the first CSI-RS resource is also referred to as a first RI, and theRI determined by the second CSI-RS resource is also referred to as asecond RI. Note that in a case that the RI is equal to or less than four(four layers), the number of codewords is one, and in a case that the RIis greater than four, the number of codewords is two. Accordingly, theCSI reported by the terminal apparatus may vary depending on whether thetotal of the first RI and the second RI is equal to or less than four,or greater than four, In a case that the total of the first RI and thesecond RI is equal to or less than four, the CQI determined inconsideration of both the first CSI-RS and the second CSI-RS isdetermined, At this time, the terminal apparatus reports the CQIdetermined in consideration of the first CRI, the second CRI, the firstRI, the second RI, and both of the first. CSI-RS and the second CSI-RSas CSI. In a case that the total of the first RI and the second. RI isgreater than four, the first CQI determined by the first CSI-RS and thesecond CQI determined by the second CSI-RS are determined. At this time,the terminal apparatus reports the first CRI, the second CRI, the firstRI, the second RI, the first CQI, and the second CQI as CSI.

In a case that the report amount is configured to the CRI, RI, PMI, orCQI in the CSI report configuration, and that the group based beamreporting is configured to be on, the terminal apparatus determines theCSI, based on two CSI-RS resources that can be received simultaneouslyby one spatial domain reception filter or multiple spatial domainreception filters. The PMI for the first CSI-RS resource is alsoreferred to as the first PMI, and the PMI for the second CSI-RS resourceis also referred to as the second PMI. Note that the first PMI and thesecond PMI may be determined in consideration of both of the first CRIand the second CRI. In this case, the first PMI and the second PMI forwhich interference between each other is considered is determined. Notethat PMI is divided into PMI-1 and PMI-2 in a case that the CSI-RS isequal to or greater than four antenna ports. The PMI-1 is widebandinformation, and indicates a codebook index that is determined based atleast on N1 and N2. Note that the number of antenna ports of the CSI-RSis represented by 2N1N2. Note that N1 and N2 are both integers of 1 orgreater, and N1 represents the number of antenna ports in the firstdimension (e.g., horizontal direction), and N2 represents the number ofantenna ports in the second dimension (e.g., vertical direction). Thenumber of polarization antennas is two. The PMI-1 includes one or morepieces of information depending on the values of N1 and N2, or the RI(the number of layers). The PMI-2 is wideband or subband information,and indicates at least the phase rotation. Note that the PMI-1 and thePMI-2 determined by the first CSI-RS resource are also referred to as afirst PMI-1 and a first PMI-2, respectively. The PMI-1 and the PMI-2determined by the second CSI-RS resource are also referred to as asecond PMI-1 and a second PMI-2, respectively, Note that the reportamount may be configured with the CRI, RI, PMI-1. and CQI. Note that theCRI, RI, and CQI are the same as the case that the report amount isconfigured with the CRI, RI, and CQI. Therefore, in a case that thetotal of the first RI and the second RI is equal to or less than four,the terminal apparatus reports the CQI determined in consideration ofthe first CRI, the second CRI, the first RI, the second RI, the firstPMI (PMI-1), the second PMI (PMI-1), and both of the first CSI-RS andthe second CSI-RS as CSI. In a case that the total of the first RI andthe second RI is greater than four, the terminal apparatus reports thefirst CRI, the second CRI, the first RI, the second RI, the first PMI(PMI-1), the second PMI (PMI-1), the first CQI, and the second CQI asCSI.

Note that in a case that the total of the first RI and the second RI isgreater than four, the number of layers of the number of codewords 1 isthe same as or smaller than the number of layers with of the number ofcodewords 2, so the first RI is the same as or smaller than the secondRI. In other words, in a case that the RI is reported, the first CRI orthe second CRI is determined by the value of RI rather than the one withbetter received power (RSRP)/received quality (RSRQ) is the first CRI.In a case that the number of layers of the codeword 1 and the number oflayers of the codeword 2 are different, the difference is 1. In otherwords, in a case that the total of the first RI and the second RI isfive, the first RI is two and the second RI is three. In a case that thetotal of the first RI and the second RI is six, the first RI is threeand the second RI is three. In a case that the total of the first RI andthe second RI is seven, the first RI is three and the second RI is four.In a case that the total of the first RI and the second RI is eight, thefirst RI is four and the second RI is four. In a case that thedifference between the first RI and the second RI is greater than one,the terminal apparatus may report the CSI of either the first CRI or thesecond CRI, for example, the one with greater value of RI. Since thereis the rule described above, the terminal apparatus may report the totalvalue of the first RI and the second RI without reporting the first RIand the second RI separately. Note that in a case that the group basedbeam reporting is configured to be on, and that the report amount isconfigured to the CRI, RI, CQI or CRI, RI, PMI (PMI-1), and CQI, thefirst CRI and the second CRI may be different codewords. At this time,the CQI is reported with the first CQI and the second CQI. However, thetotal of the first RI and the second RI is equal to or less than eight,and an RI in one CRI is equal to or less than four, Note that in a casethat the first CRI and the second CRI are different codewords, theterminal apparatus may be indicated from the base station apparatus.Note that, even in the case that the first CRI and the second CRI aredifferent codewords, in a case that the number of layers of the codeword1 and the number of layers of the codeword 2 are different, thedifference may be 1. At this time, in a case that the total of the firstRI and the second RI is four, the first RI is two and the second RI istwo. In a case that the total of the first RI and the second RI isthree, the first RI is one and the second RI is two. In a case that thetotal of the first RI and the second RI is two, the first RI is one andthe second RI is one.

The priority of the CSI report is configured to be higher for the CRIwhere the RI is greater, In other words, in the present embodiment, thesecond CRI has higher priority than that of the second CRI. For example,in a case that the amount of information of the PUCCH is insufficient,the second CRI and the RI/PMI/CQI determined by the second CRI isreported, and the first CRI and the RI/PMI/CQI determined by the firstCRI are dropped. Note that in a case that CQI is reported in either oneof the CRTs, the CQI determined by one CRI is reported even in a casethat the total of the first RI and the second RI is equal to or lessthan four.

In a case that the CSI is reported in the PUSCH, or in a case that thesubband CSI is reported in the PUCCH, the CSI is divided into two partsand reported. The two parts are also referred to as a first part (Part1, CSI part 1), and a second part (Part 2, CSI part 2). Note that thepriority of the CSI report is higher in the first part than in thesecond part. For example, in a case that. the RI is less than or equalto four, the first part includes some or all of the total of the firstRI and the second RI (or second RI), the second CRI, and the CQI basedon the first CRI and the second CRI (or the second CQI). The second partincludes some or all of the first CRI, the first RI, the first CQI, thefirst PMI, and the second PMI. In a case that the RI is greater thanfour, the first part includes some or all of the total of the first RIand the second RI (or second RI), the second CRI, and the second CQI.The second part includes some or all of the first CRI, the first RI, thefirst CQI, the first PMI, and the second PMI. Note that the CSI may bedivided into three parts. The third part is also referred to as a thirdpart (Part 3, CSI part 3). The third part has a lower priority than thatof the second part. At this time, the first part includes some or all ofthe total of the first RI and the second RI (or second RI), the secondCRI, and the CQI based on the first CRI and the second CRI (or thesecond CQI). The second part includes some or all of the first CRI, thefirst RI, and the first CQI. The third part includes some or all of thefirst PMI and the second PMI.

Note that the terminal apparatus may divide and report each of the CSIbased on the first CRI and the CSI based on the second CRI in two parts.Note that the two parts of the CSI based on the first CRI are alsoreferred to as a first part 1 and a first part 2, The two parts of theCSI based on the second CRI are also referred to as a second part 1 anda second part 2. Note that the first part 1 includes some or all of thefirst CRI, the first RI, and the first CQI. The first part 2 includesthe first PMI. The second part 1 includes some or all of the second CRI,the second RI, and the second CQI. The second part 2 includes the secondPMI. Note that the priority of CSI can be configure high in order of thesecond part 1, the first part 1, the second part 2, and the first part2. At this time, the terminal apparatus reports CSI having a long period(small variation) in the second CRI and the first CRI, and the basestation apparatus and the terminal apparatus can communicate by usingminimum parameters for the first CRI and the second CRI. The priority ofCSI can he configured high in order of the second part 1, the secondpart 2, the first part 1, and the first part 2. At this time, by theterminal apparatus preferentially reporting the complete CSI in thesecond CRI, the base station apparatus and the terminal apparatus cancommunicate by using detailed parameters related to the second CRI.

Note that in a case that the first RI and the second RI are equal to orless than four, and the first CRI and the second CRI are separatecodewords, the terminal apparatus reports information indicating thatboth or one of the CSI based on the first CRI and the CSI based on thesecond CRI are reported, Note that information indicating that both orone of the CSI based on the first CRI and the CSI based on the secondCRI are reported is included in the first part of the CSI, Note thatinformation indicating that both or one of the CSI based on the firstCRI and the CSI based on the second CRI are reported may indicatewhether or not the first CRI is included in the second part of the CSI.

The DMRS for the PDSCH or the PUSCH is configured with a DMRSconfiguration type 1 (first DMRS configuration type) or a DMRSconfiguration type 2 (second LAIRS configuration type). The DMRSconfiguration type 1 supports up to eight DMRS antenna ports, and theDMRS configuration type 2 supports up to 12 DMRS antenna ports. The DMRSis multiplexed by Code Division Multiplexing (CDM) with Orthogonal CoverCode (OCC). The OCC has a code length of up to 4 and has a length of 2in the frequency direction and a length of 2 in the time direction. Thefront-loaded DMRS is mapped at one symbol or two symbols. In a case thatthe front-loaded DMRS is one symbol, the DMRS cannot be multiplexed inthe time direction, so the DMRS is only multiplexed in the frequencydirection. This case may be referred to as OCC=2. Up to four DMRSantenna ports are multiplexed by CDM in the OCC. Note that the four DMRSantenna ports to be multiplexed by CUM is also referred to as a CDMgroup (DMRS CDM group). In this case, the DMRS configuration type 1includes two CDM groups, and the DMRS configuration type 2 includesthree CDM groups. The DMRSs of different CDM groups are mapped toorthogonal resources. Note that the two ow groups of the DMRSconfiguration type 1 are also referred to as CDM group 0 (first CDMgroup) and CDM group 1 (second CDM group). Three CDM groups of the DMRSconfiguration 2 are also referred to as CDM group 0 (first CDM group),CDM group 1 (second CDM group), and CDM group 2 (third CDM group). Forthe DMRS configuration type 1, the CUM group 0 includes DMRS antennaports 1000, 1001, 1004, and 1005, and the CDM group 1 includes DMRSantenna ports 1002, 1003, 1006, and 1007, For the DMRS configurationtype 2, the CDM group 0 includes DMRS antenna ports 1000, 1001, 1006,and 1007, the CDM group 1 includes DMRS antenna ports 1002 1003, 1008,and 1009, and the CUM group 2 includes DMRS antenna ports 1004, 1005,1010, and 1011. Note that the CDM group associated with the DMRS is alsoreferred to as a DMRS CUM group.

The DMRS antenna port number for the PDSCH or PUSCH and the number ofDMRS CDM groups without data are indicated by DCI. The terminalapparatus can recognize the number of DMRS antenna ports by the numberof indicated DMRS antenna port numbers. The number of DMRS CDM groupswithout data indicates that no PDSCH is allocated for resources on whichthe DMRSs of the associated CDM group are mapped. Note that in a casethat the number of DMRS CUM groups without data is one, the CDM group tobe referenced is the CDM group 0, and in a case that the number of DMRSCDM groups without data is two, the CUM group to be referenced is theCDM group 0 and the CDM group 1, and in a case that the number of DMRSCDM groups without data is three, the CDM group to be referenced is theCDM group 0, the CDM group 1, and the CDM group 2.

Note that, for example, in a case of transmission of Multi User-MultipleInput Multiple Output (MU-MIMO), the DMRS for the PDSCH or PUSCH can bedifferent in power from the PDSCH. For example, it is assumed that thebase station apparatus has spatially multiplexed and transmitted fourlayers of PDSCH for each of two terminal apparatuses. In other words,the base station apparatus spatially multiplexes and transmits a totalof eight layers of PDSCH. In this case, the base station apparatusindicates the DMRS antenna port numbers of the CUM group 0 to oneterminal apparatus, and indicates the DMRS antenna port numbers of theCDM group 1 to another terminal apparatus. The base station apparatusindicates that the number of DMRS CDM groups without data is two to thetwo terminal apparatuses. At this time, the spatial multiplexing orderof the DMRS is four, while the spatial multiplexing order of the PUSCHis eight, and the power ratio (offset) between the DMRS and the PDSCH istwice (different by 3 dB). For example, it is assumed that the basestation apparatus has spatially multiplexed and transmitted four layersof PDSCH for each of three terminal apparatuses. In other words, thebase station apparatus spatially multiplexes and transmits a total of 12layers of PDSCH. In this case, the base station apparatus indicates thethree terminal apparatuses with the DMRS antenna port numbers of the CUMgroup 0, the CDM group 1, and the CDM group 2 m respectively. The basestation apparatus indicates that the number of DMRS CDM groups withoutdata is three to the three terminal apparatuses. At this time, thespatial multiplexing order of the DMRS is four, while the spatialmultiplexing order of the PDSCH is 12, and the power ratio between theDMRS and the PUSCH is three times (different by 4.77 dB). Accordingly,the base station apparatus or the terminal apparatus transmits the DMRSand PDSCH in consideration of the power ratio of the DMRS and the PDSCHfor several times of the number of CDM groups. The base stationapparatus or the terminal apparatus demodulates (decodes) the PDSCH inconsideration of the power ratio of the DMRS and the PDSCH for severaltimes of the CDM groups. Note that the power ratio of the DMRS and thePDSCH of several times for the CDM groups is considered in the case ofSingle user MIMO (SU-MIMO) transmission with a large spatialmultiplexing order.

However, in a case that the terminal apparatus communicates withmultiple base station apparatuses (transmission and/or receptionpoints), the power ratio of the DMRS and the PDSCH may be different fromthose described above. For example, in a case that the terminalapparatus communicates with two base station apparatuses (transmissionand/or reception points), it is assumed that four layers of PDSCH arespatially multiplexed and transmitted from each of the base stationapparatuses. In this case, the number of DMRS CDM groups without data isindicated to be 2 from one of the base station apparatuses or two basestation apparatuses. However, since the spatial multiplexing order ofthe DMRS and the spatial multiplexing order of the PDSCH transmittedfrom each of the base station apparatuses are four, the power ratio ofthe DMRS and the PDSCH is one 1 (0 dB), and the power ratio between theDMRS and the PDSCH need not be considered. Accordingly, the terminalapparatus needs to recognize (determine) whether or not to demodulate(decode) the PDSCH in consideration of the power ratio of the DMRS andthe PDSCH. Note that in a case that the terminal apparatus communicateswith multiple base station apparatuses (transmission and/or receptionpoints), each of the base station apparatuses (transmission and/orreception points) may transmit by reducing the power of the PDSCHaccording to the number of DMRS CDM groups without data. However, inthis case, the reliability and reliability decrease.

The base station apparatus can transmit, to the terminal apparatus, thepower ratio of the DMRS and the PDSCH or information indicating whetheror not to demodulate (decode) the PDSCH in consideration of the powerratio of the DMRS and the PDSCH. In this case, the terminal apparatuscan demodulate (decode) the PDSCH in accordance with the received powerratio of the DMRS and the PDSCH or the information indicating whether ornot to demodulate (decode) the PDSCH in consideration of the power ratioof the DMRS and the PDSCH.

The terminal apparatus can determine the power ratio of the DMRS and thePDSCH from the configuration of the DMRS port group. For example, in theDMRS configuration type I, suppose that the DMRS port group 1 isconfigured (associated) with the CDM group 0, that is, the DMRS ports1000, 1001, 1004, and 1005, and the DMRS port group 2 is configured(associated) with the CDM group 1, that is, the DMRS ports 1002, 1003,1006, and 1007. At this time, in a case that the DMRS antenna portnumbers configured to the two DMRS port groups are indicated by the DCI,the terminal apparatus demodulates (decodes) the PDSCH as the powerratio of the DMRS and the PDSCH as 1 (0 dB) even in a case that thenumber of DMRS CDM groups without data is indicated two. In a case thatthe DMRS antenna port numbers configured only in one DMRS port group areindicated by the DCI, the terminal apparatus demodulates (decodes) thePDSCH as the power ratio of the DMRS and the PDSCH as 1 (0 dB).

The terminal apparatus can determine the power ratio of the DMRS and thePDSCH by the TCI. In a case that the received TCI is a configuration fortwo DMRS port groups, the terminal apparatus demodulates (decodes) thePDSCH as the power ratio of the DMRS and the PDSCH as 1 (0 dB), even ina case that the number of DMRS CUM groups without data is two or three.In other cases, the terminal apparatus determines the power ratio of theDMRS and the PDSCH according to the number of DMRS CDM groups withoutdata.

The initial value of the DMRS sequence is calculated based on at leastthe NID and the SCID. The SCID is configured at most in two Ids and isindicated as 0 or 1. The NID is associated with the SCID and isconfigured by higher layer signaling. For example, NID for SCID=0 andNID for SCID=1 are configured. In a case that the N or SCID is notconfigured, the SCID is SCID=0 and the NID is a physical cell ID. TheSCID is included in the DCI. The SCID may indicate whether or not todemodulate (decode) the PDSCH in consideration of the power ratio of theDMRS and the PDSCH. For example, in a case of SCID=0, the terminalapparatus demodulates (decodes) the PDSCH in consideration of the powerratio of the DMRS and the PDSCH according to the number of DMRS CDMgroups without data, and in a case of SCID=1, the terminal apparatusdemodulates (decodes) the PDSCH without considering the power ratio ofthe DMRS and the PDSCH. The SCID and DMRS port groups may be associatedwith each other. For example, a sequence of SCID=0 is generated for theDMRS associated with the DMRS port group 1, and a sequence of SCID=1 isgenerated for the DMRS associated with the DMRS port group 2.

Note that in a case that multiple base station apparatuses (transmissionand/or reception points) communicate with a terminal apparatus, and thateach of the base station apparatuses transmits a PDCCH to the terminalapparatus in the same slot, each of the base station apparatuses canspatial multiplex different terminal apparatuses by MU-MIMO. Forexample, consider a case of transmitting PDCCH 1 (DCI 1) from the basestation apparatus 3A to the terminal apparatus 4A and transmitting thePDCCH 2 (DCI 2) from the base station apparatus 5A to the terminalapparatus 4A. Note that the PDCCH 1 and the PDCCH 2 are transmitted inthe same slot. Although not illustrated, it is assumed that the basestation apparatus 5A spatially multiplexes the terminal apparatus 4A andthe terminal apparatus 4B. Assuming the DMRS configuration type 2, andit is also assumed that the base station apparatus 3A configures theDMRS ports 1000, 1001, 1006, and 1007 as the DMRS port group 1, andconfigures the DMRS ports 1002, 1003, 1008, and 1009 as the DMRS portgroup 2 for the terminal apparatus 4A. The DMRS port numbers included inthe DCI 1 are 1000, 1001, 1006, and 1007, and the number of CDM groupswithout data is two. The DMRS port numbers included in the DCI 1 are1002, 1003, 1008, and 1009, and the number of CDM groups without data isthree. At this time, the base station apparatus 5A communicates with theterminal apparatus 4B by using the DMRS port numbers 1004, 1005, 1010,and 1011, At this time, the terminal apparatus 4A recognizes that theDMRS of the DMRS port group 1 is indicated by the DCI 1, and the DMRS ofthe DMRS port group 2 is indicated by the DCI 2. Therefore, since twoDMRS CDM groups without data indicated by the DCI 1 is used for thetransmission addressed to the apparatus itself, it is possible todetermine that the power ratio to the PDSCH corresponding to the DMRSDMRS ports 1000, 1001, 1006, and 1007 indicated by the DCI 1 is 1 (0dB). Since two CDM groups without data of the three CDM groups withoutdata indicated by the DCI 2 are used for the transmission addressed tothe apparatus itself, it is possible to determine that the power ratioto the PDSCH corresponding to the DMRS ports 1002, 1003, 1008, and 1009indicated by the DCI 2 is 2 (3 dB). In other words, in a case that theterminal apparatus receives two PDCCHs in the same slot, the terminalapparatus can determine the power ratio of the DMRS and the PDSCH, inconsideration of the number of subtracting 1 from the number of DMRS CDMgroups without data indicated in one DCI.

The same or different pieces of data can be transmitted from multiplebase station apparatuses (transmission and/or reception points) on onePDCCH.

The base station apparatus 3A and the base station apparatus 5A can beconfigured for either transmitting the same downlink data ortransmitting different downlink data, based on the number of transportblocks configured by the DCI 1, For example, in a case that the numberof transport blocks configured by the DCI 1 is one, the base stationapparatus 3A and the base station apparatus 5A can transmit the samedownlink data. At this time, the base station apparatus 3A and the basestation apparatus 5A can transmit the same downlink data by the sameDMRS port, or can transmit the same downlink data by different DMRSports. The base station apparatus 3A and the base station apparatus 5Acan be configured with the DMRS port for transmitting the downlink data,based on the number of layers configured by the DCI 1 and the number oflayers limited for each transmission and/or reception point. Accordingto another example, in a case that the number of transport blocksconfigured by the DCI 1 is two, the base station apparatus 3A and thebase station apparatus 5A can transmit different downlink data, At thistime as well, the base station apparatus 3A and the base stationapparatus 5A can transmit the downlink data by the same DMRS port, orcan transmit the downlink data by different DMRS ports. Thus, theterminal apparatus 4A can determine, based on the number of transportblocks configured by the DCI 1, whether the same downlink data istransmitted or different downlink data is transmitted from the multiplebase station apparatuses, for the received downlink data. Note that in acase that one transport block is configured to be indicated by one PDCCH(DCI) in higher layer signaling, the terminal apparatus 4A may notassume that different downlink data is transmitted from multiple basestation apparatuses in one PDCCH (for example, DMRS ports that are notQCL).

The base station apparatus 3A and the base station apparatus 5A can beconfigured for either transmitting the same downlink data ortransmitting different downlink data, based on the number of layers (thenumber of DMRS ports) configured by the DCI 1. In other words, in a casethat a value greater than or equal to a prescribed value is configuredto the number of layers configured by the DCI 1, the base stationapparatus 3A and the base station apparatus 5A can transmit the samedownlink data. The base station apparatus 3A and the base stationapparatus 5A can be configured for whether to transmit the same downlinkdata or to transmit different downlink data, based on the slot size(size of the mini-slot) or subcarrier spacing configured in the downlinkdata. In a case that the base station apparatus 3A and the base stationapparatus 5A transmit downlink data in slots including less than 14 OFDMsymbols, the same downlink data can be transmitted. In a case that thebase station apparatus 3A and the base station apparatus 5A transmitdownlink data at subcarrier spacing wider than 15 KHz, the same downlinkdata can be transmitted. Thus, the terminal apparatus 4 can determine,based on the number of layers (the number of DMRS ports) configured bythe DCI 1 and the slot size or subcarrier spacing configured to thehigher layer and the DCI 1, whether the same downlink data istransmitted or different downlink data is transmitted from the multiplebase station apparatuses, for the received downlink data.

The base station apparatus 3A and the base station apparatus 5A can beconfigured for either transmitting the same downlink data ortransmitting different downlink data in accordance with the frequencyband. In other words, the base station apparatus 3A and the base stationapparatus 5A can transmit the same downlink data in a frequency band ata prescribed frequency or higher. In a case that the base stationapparatus 3A and the base station apparatus 5A have different frequencybands for transmitting downlink data, the base station apparatus 3A andthe base station apparatus 5A can transmit the same downlink data. Thus,the terminal apparatus 4 can determine whether the same downlink data istransmitted or different downlink data is transmitted from the multiplebase station apparatuses, based on the frequency band configured to thebase station apparatus to which the terminal apparatus 4 connects.

The base station apparatus 3A and the base station apparatus 5A candescribe information indicating whether the base station apparatus 3Aand the base station apparatus 5A transmit the same downlink data ortransmit different downlink data to CSI configuration informationrequired by the terminal apparatus 4A, trigger information requestingCSI, or CSI-RS configuration information. The terminal apparatus 4A canconfigure the CSI calculation method, the information included in theCSI, the feedback period, and the like, based on whether the informationcan be understood or not. For example, in a case that the triggerinformation requesting the CSI is described with information indicatingthat the base station apparatus 3A and the base station apparatus 5Atransmit the same downlink data, the terminal apparatus 4A calculatesthe RI from the value smaller than or equal to a prescribed value as theCSI, rather than feeding back RI calculated from the received referencesignal (e.g., CSI-RS), in calculating the CSI. For example, the terminalapparatus 4A can assume that the base station apparatus 3A and the basestation apparatus 5A transmit different downlink data, divide the CSI-RS(CSI-RS port) into multiple groups (or multiple CSI-RS resources areconfigured) based on a prescribed rule (for example, information on QCL,or the like), calculate the CSI for each group (CSI-RS resource), andfeedback (report) the CSI to the base station apparatus. Note that in acase that multiple CSI-RS groups (CSI-RS resources) are transmitted(configured), and that the terminal apparatus 4A can receive multipleCSI-RS groups (CSI-RS resources) simultaneously (at the same timing) inone or more spatial reception filters (receive beam directions), theterminal apparatus 4A can measure (calculate) and report the CSI, basedon the multiple CSI-RS groups (CSI-RS resources). At this time, the CSIseparately calculated by the terminal apparatus 4A can be calculatedassuming the same target quality (target packet (block) error rate).However, the target quality may be a different value, assuming whetherthe base station apparatus 3A and the base station apparatus 5A transmitthe same downlink data or transmit different downlink data. For example,in a case that the target packet (block) error rate is assumed to be0.1, the terminal apparatus 4A can measure (calculate) the CSI assumingthat different downlink data has been transmitted from the two basestation apparatuses. For example, in a case that the target packet(block) error rate is assumed to be less than 0.1 (e.g., 0.00001), theterminal apparatus 4A can measure (calculate) the CSI assuming that thesame downlink data has been transmitted from the two base stationapparatuses. Note that the target packet (block) error rate may beassociated with the CQI (MCS) table.

For example, the PDCCH 1 (DCI 1) can be transmitted from the basestation apparatus 3A to the terminal apparatus 4A, and the same ordifferent downlink data (transport blocks) can be transmitted to theterminal apparatus 4A from the base station apparatus 3A and the basestation apparatus 5A. At this time, the base station apparatus 3A andthe base station apparatus 5A may transmit downlink data by using thesame DMRS port, or may transmit downlink data by using different DMRSports. In a case that the base station apparatus 3A and the base stationapparatus 5A transmit different downlink data on the same DMRS port, theDCI 1 includes two TCIs for which the QCL type D is configured. In acase that the base station apparatus 3A and the base station apparatus5A transmit the same downlink data on the same DMRS port, the DCI 1includes one or two TCIs for which the QCL type D is configured. Notethat in a case that two TCIs for which the QCL type D is configured isincluded in the DCI 1, the first TCI and the second TCI may indicate thesame content (the receive beam, the spatial reception filter).

In a case that the number of DMRS ports included in the DCI 1 is greaterthan or equal to five, the base station apparatus 3A and the basestation apparatus 5A can transmit the same downlink data on the sameDMRS port, or the base station apparatus 3A and the base stationapparatus 5A can transmit different downlink data on different DMRSports. Note that, in order to reduce the number of layers that theterminal apparatus 4A demodulates at a time, in a case that multiplebase station apparatuses (transmission and/or reception points) transmitthe same downlink data in one PDCCH and in a case that multiple basestation apparatuses (transmission and/or reception points) transmitdifferent downlink data in one PDCCH, each base station apparatus(transmission and/or reception point) may be limited to transmission offour or fewer layers. At this time, in a case that the number of DMRSports included in the DCI 1 is greater than or equal to five, the basestation apparatus 3A and the base station apparatus 5A transmitdifferent downlink data on different DMRS ports.

Note that, in a case that multiple base station apparatuses(transmission and/or reception points) transmit different downlink datain one PDCCH in order to reduce the number of layers that the terminalapparatus 4A demodulates at a time, each base station apparatus(transmission and/or reception point) may be limited to transmission offour or fewer layers, and in a case that multiple base stationapparatuses (transmission and/or reception points) transmit the samedownlink data in one PDCCH, the number of transmission layers of eachbase station apparatus (transmission and/or reception point) may not belimited. At this time, in a case that the number of DMRS ports (thenumber of layers) included in the DCI 1 is greater than or equal tofive, the base station apparatus 3A and the base station apparatus 5Atransmit the same downlink data on the same DMRS port, or the basestation apparatus 3A and the base station apparatus 5A transmitdifferent downlink data on different DMRS ports. Note that, in order toavoid the complexity of the terminal apparatus 4A, in a case that thenumber of DMRS ports (the number of layers) included in the DCI 1 isgreater than or equal to five, it may be limited whether the basestation apparatus 3A and the base station apparatus 5A transmit the samedownlink data on the same DMRS port, or the base station apparatus 3Aand the base station apparatus 5A transmit different downlink data ondifferent DMRS ports.

In a case that the number of DMRS ports (the number of layers) includedin the DCI 1 is equal to or less than four, the base station apparatus3A and the base station apparatus 5A can transmit the same downlink dataon different DMRS ports, the base station apparatus 3A and the basestation apparatus 5A can transmit different downlink data on differentDMRS ports, or the base station apparatus 3A and the base stationapparatus 5A can transmit different downlink data on the same DMRS port.Note that in a case that the base station apparatus 1A and the basestation apparatus 5A transmit different downlink data, and that thenumber of DMRS ports (the number of layers) indicated by the DCI 1 isequal to or less than four, the base station apparatus 3A and the basestation apparatus 5A can transmit two codewords (transport blocks). Inthis case, in a case that the number of DMRS ports (the number oflayers) included in the DCI 1 is equal to or less than four, and thatthe number of transport blocks configured by the DCI 1 is one, the basestation apparatus 3A and the base station apparatus 5A transmit the samedownlink data on different DMRS ports. In a case that the number of DMRSports (the number of layers) included in the DCI 1 is equal to or lessthan four, and that the number of transport blocks configured by the DCI1 is two, the base station apparatus 3A and the base station apparatus5A transmit different downlink data on different DMRS ports. Note that,in a case that the number of DMRS ports (the number of layers) indicatedby the DCI 1 is equal to or less than four, and that the base stationapparatus 3A and the base station apparatus 5A do not transmit or areconfigured not to transmit two codewords (transport blocks), and thatthe number of transport blocks configured by the DCI 1 is two, the basestation apparatus 3A and the base station apparatus 5A transmitdifferent downlink data on the same DMRS port.

For example, two DMRS port groups can be configured, the PDCCH 1 (DCI 1)can be transmitted from the base station apparatus 3A to the terminalapparatus 4A, and the base station apparatus 3A and the base stationapparatus 5A can transmit the same or different downlink data (transportblocks) on different DMRS ports to the terminal apparatus 4A. In a casethat the number of transport blocks configured by the DCI 1 is one, thebase station apparatus 3A and the base station apparatus 5A transmit thesame downlink data. In a case that the number of transport blocksconfigured by the DCI 1 is two, the base station apparatus 3A and thebase station apparatus 5A transmit different downlink data. Note thateach DMRS port group can transmit one codeword (transport block). Inthis case, in a case that the number of DMRS ports (the number oflayers) included in the DCI 1 is equal to or less than four and the DMRSports belong to two DMRS port groups, and that the number of transportblocks configured by the DCI 1 is one, the base station apparatus 3A andthe base station apparatus 5A transmit the same downlink data ondifferent DMRS ports. In a case that the number of DMRS ports (thenumber of layers) included in the DCI 1 is equal to or less than fourand the DMRS ports belong to two DMRS port groups, and that the numberof transport blocks configured by the DCI 1 is two, the base stationapparatus 3A and the base station apparatus 5A transmit differentdownlink data on different DMRS ports. Note that, in order to reduce thenumber of layers that the terminal apparatus 4A demodulates at a time,in a case that multiple base station apparatuses (transmission and/orreception points) transmit the same or different downlink data in onePDCCH, each base station apparatus may be limited to transmission offour or fewer layers. At this time, in a case that the number of DMRSports (the number of layers) included in the DCI 1 is greater than orequal to five, the base station apparatus 3A and the base stationapparatus 5 transmit different downlink data. Note that in a case thattwo TCIs for which the QCL. type D is configured is included in the DCI1, the first TCI is associated with the first DMRS port group, and thesecond TCI is associated with the second DMRS port group.

In a case that two DMRS port groups are configured, it may mean thateach DMRS port group transmits different downlink data. In this case, ina case that two DMRS port groups are not configured, the base stationapparatus 3A and the base station apparatus 5A transmit the samedownlink data.

Note that the configuration of the transport block included in the DCIincludes an MCS, RV, and New Data Indicator (NDI). Note that, in a casethat the transport block is disabled, the base station apparatusconfigures the MCS to be 26 and the RV to be 1. Accordingly, theterminal apparatus can determine whether the transport block is enabledor disabled from the configuration value (parameter) of the transportblock included in the DCI. Note that the number of transport blocksconfigured by the DCI indicates the number of transport blocks that areenabled (not disabled).

In a case that the PDCCH 1 (DCI 1) is transmitted from the base stationapparatus 3A to the terminal apparatus 4A, and the base stationapparatus 3A and the base station apparatus 5A transmit the same ordifferent downlink data on the same or different DMRS ports, theterminal apparatus 4A needs to receive the PDCCH 1 (DCI 1) and determinewhether the base station apparatus 3A and the base station apparatus 5Atransmit the same or different downlink data on the same or differentDMRS ports. In a case that one TCI for which the QCL, type D included inthe DCI 1 is configured is included, the terminal apparatus 4A receivesby the spatial reception filter indicated by the TCI and demodulates thePDSCH. In a case that two TCIs for which the QCL type D included in theDCI 1 is configured is included, the terminal apparatus 4A can determinethat the same/or different downlink data is received at the same ordifferent DMRS ports from the base station apparatus 3A and the basestation apparatus 5A. At this time, in a case that the number of DMRSports indicated by the DCI 1 is greater than or equal to five, theterminal apparatus 4A can determine that the same downlink data isreceived at the same DMRS port from the base station apparatus 3A andthe base station apparatus 5A, or different downlink data is received atdifferent DMRS ports from the base station apparatus 1A and the basestation apparatus 5A. In a case that multiple base station apparatuses(transmission and/or reception points) transmit different downlink datain one PDCCH, each base station apparatus (transmission and/or receptionpoint) may be limited to transmission of four or fewer layers. At thistime, in a case that the number of DMRS ports indicated by the DCI 1 isgreater than or equal to five, the terminal apparatus 4A can determinethat the same downlink data is received at the same DMRS port from thebase station apparatus 3A and the base station apparatus 5A. Note thatin a case that multiple base station apparatuses (transmission and/orreception points) transmit the same or different downlink data in onePDCCH, each base station apparatus (transmission and/or reception point)may be limited to transmission of four or fewer layers. At this time, ina case that the number of DMRS ports indicated by the DCI 1 is greaterthan or equal to five, the terminal apparatus 4A can determine thatdifferent downlink data is received at different DMRS ports from thebase station apparatus 3A and the base station apparatus 5A. In a casethat the terminal apparatus 4A determines that the same downlink data isreceived at the same DMRS port from the base station apparatus 3A andthe base station apparatus 5A, the terminal apparatus 4A selects orcombines and demodulates the first PDSCH received based on the first TCIof the two TCIs for which the QCL type D included in the DCI 1 isconfigured, and the second PDSCH received based on the second TCI, anddecodes the two transport blocks, In a case that the terminal apparatus4A determines that different downlink data is received at different DMRSports from the base station apparatus 3A and the base station apparatus5A, the terminal apparatus 4A divides the DMRS ports indicated by theDCI 1 into two numbers of layers (transport blocks, codeword),demodulates the first PDSCH received based on the first TCI to decodethe first transport block, and demodulates the second PDSCH receivedbased on the second TCI to decode the second transport block. In a casethat the number of DMRS ports indicated by the DCI 1 is equal to or lessthan four, the terminal apparatus 4A receives the same downlink data atdifferent DMRS ports from the base station apparatus 3A and the basestation apparatus 5A, receives different downlink data at different DMRSports from the base station apparatus 3A and the base station apparatus5A, or receives different downlink data at the same DMRS port from thebase station apparatus 3A and the base station apparatus 5A. Note thatin a case that the base station apparatus 3A and the base stationapparatus 5A transmit different downlink data, and that the number ofDMRS ports (the number of layers) indicated by the DCI 1 is equal to orless than four, the base station apparatus 3A and the base stationapparatus 5A can transmit two codewords (transport blocks). At thistime, in a case that the number of DMRS ports (the number of layers)indicated by the DCI 1 is equal to or less than four, and that thenumber of transport blocks configured by the DCI 1 is one, the terminalapparatus 4A can determine that the same downlink data is received atdifferent DMRS ports. In a case that the number of DMRS ports (thenumber of layers) indicated by the DCI 1 is equal to or less than four,and that the number of transport blocks configured by the DCI 1 is two,the terminal apparatus 4A can determine that different downlink data isreceived at different DMRS ports. In a case that the terminal apparatus4A determines that the same downlink data is received at different DMRSports from the base station apparatus 3A and the base station apparatus5A, the terminal apparatus 4A divides the DMRS ports indicated by theDCI 1 into two layers, selects or combines and demodulates the firstPDSCH received based on the first To and the second PDSCH received basedon the second TCI, and decodes one transport block. Note that in thiscase, the number of DMRS ports (the number of layers) indicated by theDCI 1 and the number of DMRS ports in the transport block (the number oflayers) are different, so the terminal apparatus 4A calculates thetransport block size, based on the number of DMRS ports (the number oflayers) of the transport block. In a case that the terminal apparatus 4Adetermines that different downlink data is received at different DMRSports from the base station apparatus 3A and the base station apparatus5A, the terminal apparatus 4A demodulates the first PDSCH received basedon the first TCI to decode the first transport block, and demodulatesthe second PDSCH received based on the second TCI to decode the secondtransport block. Note that, in the case that the number of DMRS ports(the number of layers) indicated by the DCI 1 is equal to or less thanfour, and that the base station apparatus 3A and the base stationapparatus 5A do not transmit or are configured not to transmit twocodewords (transport blocks), and that the number of transport blocksconfigured by the DCI 1 is two, the terminal apparatus 4A can determinethat different downlink data is received at the same DMRS port from thebase station apparatus 3A and the base station apparatus 5A. In a casethat the terminal apparatus 4A determines that different downlink datais received at the same DMRS port from the base station apparatus 3A andthe base station apparatus 5A, the terminal apparatus 4A demodulates thefirst PDSCH received at the first TCI with the number of DMRS ports (thenumber of layers) indicated by, the DCI 1 to decode the first transportblock, and demodulates the second PDSCH received at the second TCI withthe number of DMRS ports (the number of layers) indicated by the DCI 1to decode the second transport block, The terminal apparatus 4Atransmits the ACK/NACK information of the first transport block and thesecond transport block with the PUCCH resource indicated by the DCI 1.

In a case that two DMRS port groups are configured, the PDCCH 1 (DCI 1)is transmitted from the base station apparatus 3A to the terminalapparatus 4A, and the base station apparatus 3A and the base stationapparatus 5A transmit the same or different downlink data (transportblock) to the terminal apparatus 4A at different DMRS ports, theterminal apparatus 4A needs to receive the PDCCH 1 (DCI 1) and determinewhether the base station apparatus 3A and the base station apparatus 5Atransmit the same or different downlink data on different DMRS ports. Ina case that the number of transport blocks configured by the DCI 1 isone, the terminal apparatus 4A can determine that the same downlink datais received from the base station apparatus 3A and the base stationapparatus 5A. In this case, the terminal apparatus 4A selects orcombines the first PDSCH demodulated in the DMRS of the first DMRS portgroup and the second PDSCH demodulated in the second DMRS port group todecode one transport block. In a case that the number of transportblocks configured by the DCI 1 is two, the terminal apparatus 4A candetermine that different downlink data is received from the base stationapparatus 3A and the base station apparatus 5A. In this case, theterminal apparatus 4A demodulates the first PDSCH in the DMRS of thefirst DMRS port group to decode the first transport block, anddemodulates the second PDSCH in the DMRS of the second DMRS port groupto decode the second transport block. Note that each DMRS port group cantransmit one codeword (transport block). In this case, in a case thatthe number of DMRS ports (the number of layers) included in the DCI 1 isequal to or less than four and the DMRS ports belong to two DMRS portgroups, and that the number of transport blocks configured by the DCI 1is one, the terminal apparatus 4A can determine that the same downlinkdata is received at different DMRS ports from the base station apparatus3A and the base station apparatus 5A. Note that in this case, the numberof DMRS ports (the number of layers) indicated by the DCI 1 and thenumber of DMRS ports in the transport block (the number of layers) aredifferent, so the terminal apparatus 4A calculates the transport blocksize, based on the number of DMRS ports (the number of layers) of thetransport block. In a case that the number of DMRS ports (the number oflayers) included in the DCI 1 is equal to or less than four and the DMRSports belong to two DMRS port groups, and that the number of transportblocks configured by the DCI 1 is two, the terminal apparatus 4A candetermine that different downlink data are received at different DMRSports from the base station apparatus 3A and the base station apparatus5A. Note that, in order to reduce the number of layers that the terminalapparatus 4A demodulates at a time, in a case that multiple base stationapparatuses (transmission and/or reception points) transmit the same ordifferent downlink data in one PDCCH, each base station apparatus may belimited to transmission of four or fewer layers. At this time, in a casethat the number of DMRS ports (the number of layers) included in the DCI1 is greater than or equal to five, the terminal apparatus 4A candetermine that different downlink data is received from the base stationapparatus 3A and the base station apparatus 5. Note that in a case thattwo TCIs for which the QCL type D is configured is included in the DCI1, the first. TCI is associated with the first DMRS port group, and thesecond TCI is associated with the second DMRS port group. At this time,the terminal apparatus 4A receives the DMRS of the first DMRS port groupbased on the first TCI and receives the DMRS of the second DMRS portgroup based on the second TCI.

In a case that two DMRS port groups are configured, it may mean thateach DMRS port group transmits different downlink data. In this case, ina case that two DMRS port groups are not configured, the terminalapparatus 4A can determine that the same downlink data is received fromthe base station apparatus 3A and the base station apparatus 5A. In acase that two DMRS port groups are configured, the terminal apparatus 4Acan determine that the same downlink data is received from the basestation apparatus 3A and the base station apparatus 5A.

The terminal apparatus can assume, by the configuration of the TCI,whether the base station apparatus 3A and the base station apparatus 5Atransmit the same downlink signal or transmit different downlinksignals. For example, the terminal apparatus can configure the receptionoperation based on the value of Threshold-Sched-Offset, which isinformation associated with the offset (scheduling offset) between theresource for which the DCI is configured and the resource for which thePDSCH associated with the DCI is configured. For example, in a case thatthe offset between the resource for which the DCI is configured and theresource for which the PDSCH associated with the DCI is configured isless than a prescribed value (e.g., Threshold-Sched-Offset), theterminal apparatus configures the reception operation assuming whetherthe base station apparatus 3A and the base station apparatus 5A transmitthe same downlink signal or transmit different downlink signals inadvance, by higher layer signaling or the like. The terminal apparatusconfigures the reception operation by assuming whether the base stationapparatus 3A and the base station apparatus 5A transmit the samedownlink signal or transmit different downlink signals, based on the TCIstate specified by the smallest index in multiple configured TCI states,In other words, the terminal apparatus can configure the receptionoperation, based on the configuration of the TCI default. Note that in acase that the terminal apparatus performs the reception operation basedon the configuration of the TCI default, the terminal apparatus decodesdownlink data (transport block) receivable in one spatial receptionfilter (receive beam direction). At this time, as the HARQ-ACK of thedownlink data (transport block) that is failed to be received, NACK maybe reported, information indicating failure to receive (e.g.,Discontinuous Transmission (DTX), for example) may be reported, ornothing may be transmitted.

The terminal apparatus may receive inter-user interference from aserving cell or interference signals from neighbor cells. The terminalapparatus can improve reliability and throughput by canceling orsuppressing the interference signals. In order to cancel or suppress theinterference signals, parameters of the interference signals arerequired. The interference signals are PDSCHs, PDCCHs, or referencesignals addressed to neighbor cells/other terminal apparatuses. Schemesfor canceling or suppressing interference signals to apply includeEnhanced-Minimum Mean Square Error (E-MMSE) to estimate the channels ofthe interference signals and suppress the interference by linear weight,an interference canceler that generates an interference signal replicato cancel the interference, Maximum Likelihood Detection (MLD), in whichthe desired signal and all of the interference signal transmissionsignal candidates are searched to detect the desired signal, and Reducedcomplexity-MLD (R-MLD) with a lower computation amount than the MLD byreducing the transmission signal candidates. In order to apply theseschemes, channel estimation of the interference signals, demodulation ofthe interference signals, or decoding of the interference signals isrequired.

In order to efficiently cancel or suppress the interference signals, theterminal apparatus needs to recognize the parameters of the interferencesignals (neighbor cells). Thus, the base station apparatus can transmit(configure) assistance information including the parameters of theinterference signals (neighbor cells) to the terminal apparatus toassist in the cancellation or suppression of the interference signals bythe terminal apparatus. One or more pieces of assistance information areconfigured. The assistance information may include, for example, some orall of a physical cell ID, a virtual cell ID, a power ratio (poweroffset) between the reference signal and the PDSCH, a scramblingidentity of the reference signal, a quasi co-location (QCL) information,a CSI-RS resource configuration, the number of CSI-RS antenna ports, asubcarrier spacing, resource allocation granularity, resource allocationinformation, Bandwidth Part Size configuration, DMRS configuration, DMRSantenna port numbers, the number of layers, a TDD DL/UL configuration,PMI, RI, a modulation scheme, Modulation and coding scheme (MCS), a TCIstate, and PT-RS information. Note that the virtual cell ID is an IDvirtually allocated to the cell, and cells may have the same physicalcell ID and different virtual cell IDs. The QCL information isinformation about QCL for a prescribed antenna port, a prescribedsignal, or a prescribed channel. The subcarrier spacing indicatessubcarrier spacing of the interference signals or candidates forsubcarrier spacing that may be used in the hand. Note that, in a casethat the subcarrier spacing included in the assistance information isdifferent from the subcarrier spacing used in the communication with theserving cell, the terminal apparatus may not cancel or suppress theinterference signals. The candidates for subcarrier spacing that may beused in the band may indicate a commonly used subcarrier spacing. Forexample, the commonly used subcarrier spacing may not include a lowfrequency subcarrier spacing as used for high reliability, low latencycommunication (emergency communication). The resource allocationgranularity indicates the number of resource blocks in which theprecoding (beamforming) does not change. The DMRS configurationindicates some or all of the PDSCH mapping type, the additionalallocation of the DMRS, the power ratio of the DMRS to the PDSCH, theDMRS configuration type, the number of symbols of the front-loaded DMRS,and the information indicating OCC=2 or 4. The DMRS resource allocationvaries depending on the PDSCH mapping type. For example, the PDSCHmapping type A maps the DMRS to the third symbol of the slot. Forexample, the PDSCH mapping type B maps the DMRS to the first OFDM symbolof the allocated PDSCH resource. The additional allocation of the DMRSindicates whether or not there is an additional DMRS allocation, orindicates the additional allocation. The PT-RS information includes someor all of the presence (presence/absence) of the PT-RS, the number ofports in the VT-RS, the time density, the frequency density, theresource allocation information, the associated DMRS ports (DMRS portgroup), and the power ratio of the PT-RS and the PDSCH. Note that someor all of the parameters included in the assistance information aretransmitted (configured) by the higher layer signaling. Some or all ofthe parameters included in the assistance information are transmitted inthe downlink control information. In a case that each of the parametersincluded in the assistance information indicates multiple candidates,the terminal apparatus performs blind detection of a preferable one fromamong candidates. The parameters not included in the assistanceinformation is blind detected by the terminal apparatus.

In a case that the terminal apparatus communicates by using multiplereceive beam directions, the ambient interference conditions varygreatly depending on the receive beam directions. For example, aninterference signal that is strong in one receive beam direction may beweaker in another receive beam direction. The assistance information ofthe cell that is unlikely to have strong interference may not only bemeaningless, but may also be wasteful for calculating in determiningwhether or not a strong interference signal is received. Accordingly, itis preferable that the assistance information be configured for eachreceive beam direction. However, since the base station apparatus doesnot necessarily recognize the reception direction of the terminalapparatus, information related to the receive beam direction andassistance information may be associated with each other. For example,since the terminal apparatus can associate the CRI with the receive beamdirection, the base station apparatus can transmit (configure) one ormore pieces of assistance information for each CRI. Since the terminalapparatus can associate time indexes of the synchronization signal blockand the receive beam direction, the base station apparatus can transmit(configure) one or more pieces of assistance information for each timeindex of the synchronization signal block. Since the terminal apparatuscan associate the PMI (antenna port number) with the receive beamdirection, the base station apparatus can transmit (configure) one ormore pieces of assistance information for each PMI (antenna portnumber). In a case that the terminal apparatus includes multiplesubarrays, the receive beam direction is likely to change for eachsubarray, so the base station apparatus can transmit (configure) one ormore pieces of assistance information for each index associated with thesubarrays of the terminal apparatus. For example, since the terminalapparatus can associate the TCI with the receive beam direction, thebase station apparatus can transmit (configure) one or more pieces ofassistance information for each TCI. In a case that multiple basestation apparatuses (transmission and/or reception points) communicatewith a terminal apparatus, the terminal apparatus is likely tocommunicate in a receive beam direction different from each of the basestation apparatuses (transmission and/or reception points). Thus, thebase station apparatus transmits (configures) one or more pieces ofassistance information for each information indicating the base stationapparatus (transmission and/or reception point). The informationindicating the base station apparatus (transmission and/or receptionpoint) may be a physical cell ID or a virtual cell ID. In a case thatdifferent DMRS antenna port numbers are used for the base stationapparatuses (transmission and/or reception points), informationindicating the DMRS antenna port number or the DMRS antenna group isinformation indicating the base station apparatus (transmission and/orreception point).

Note that the number of pieces of assistance information configured bythe base station apparatus for each CRI/TCI may be common. Here, thenumber of pieces of assistance information refers to the type ofassistance information, the number of elements of each assistanceinformation (e.g., the number of candidates for a cell ID), and thelike. The number of pieces of assistance information configured by thebase station apparatus for each CRI/TCI can be configured to a maximumvalue, and the base station apparatus can configure the assistanceinformation for each CRI/TCI within the range of the maximum value.

Note that in a case that the value of the scheduling offset indicatingthe scheduling start position of the terminal apparatus is less than orequal to a prescribed value, it may cause a situation in which theterminal apparatus does not finish decoding of the DCI in time for thereception of the PDSCH. At this time, the terminal apparatus can receivethe PDSCH in accordance with a default configuration (e.g., TCI default)configured in advance. In a case that interference suppression isperformed, and that the scheduling offset is less than or equal to aprescribed value, the reception of the PDSCH (configuration of thespatial domain reception filter) follows the default configuration.However, for interference suppression, even in a case that thescheduling offset is less than or equal to a prescribed value, it ispossible to follow the assistance information notified with the DCI. Thebase station apparatus can configure the terminal apparatus thatreceives the PDSCH in accordance with the TCI default so as to notperform interference suppression on the PDSCH received in accordancewith the TCI default. in other words, the terminal apparatus can performthe reception operation without assuming interference suppression on thePDSCH received in accordance with the TCI default.

Note that in a case that the receive beam direction of the terminalapparatus changes, it is likely that the transmit antennas are not QCL.Accordingly, the assistance information can be associated with the QCLinformation. For example, in a case that the base station apparatustransmits (configures) assistance information of multiple cells, thebase station apparatus can indicate cells which are QCL (or cells whichare not QCL) to the terminal apparatus.

Note that the terminal apparatus cancels or suppresses the interferencesignal by using assistance information associated with the CRI/TCI usedfor communication with the serving cell.

The base station apparatus may configure assistance informationassociated with the receive beam direction (CRI/time index of thesynchronization signal block/PMI/antenna port number/subarray/TCI) andassistance information not associated with the receive beam direction(CRI/time index of the synchronization signal block/PMI/antenna portnumber/subarray/TCI). The assistance information associated with thereceive beam direction and the assistance information not associatedwith the receive beam direction may be selectively used depending on thecapability or category of the terminal apparatus. The capability orcategory of the terminal apparatus may indicate whether or not theterminal apparatus supports receive beamforming. The assistanceinformation associated with the receive beam direction and theassistance information not associated with the receive beam directionmay be selectively used depending on the frequency band. For example,the base station apparatus does not configure the assistance informationassociated with the receive beam direction at frequencies lower than 6GHz. For example, the base station apparatus configures the assistanceinformation associated with the receive beam direction only atfrequencies higher than 6 GHz.

Note that the CRI may be associated with the CSI-RS resource setconfiguration ID. In a case that the base station apparatus indicatesthe CRI to the terminal apparatus, the base station apparatus mayindicate the CRI and the CSI-RS resource set configuration ID together.Note that in a case that the CSI-RS resource set configuration ID isassociated with one CRI or one receive beam direction, the base stationapparatus may configure the assistance information for each CSI-RSresource set configuration ID.

In a case that the terminal apparatus cancels or suppresses interferencebetween users, it is desirable for the base station apparatus toindicate that multi user transmission is likely to be performed to theterminal apparatus. The multi user transmission requiring interferencecancellation or suppression by the terminal apparatus is also referredto as multi user MIMO transmission, Multi User SuperpositionTransmission, and Non-Orthogonal Multiple Access (NOMA). The basestation apparatus can configure multi user MIMO transmission (MUST,NOMA) with higher layer signaling. In a case that multi user MIMOtransmission (MUST, NOMA) is configured, the base station apparatus cantransmit interference signal information for canceling or suppressinginter-user interference with the DCI. The interference signalinformation included in the DCI includes some or all of the presence ofthe interference signal, the modulation scheme of the interferencesignal, the DMRS port number of the interference signal, the number ofDMRS CDM groups without data of the interference signal, the power ratioof the DMRS and the PDSCH, the number of symbols of the front-loadedDMRS, the information indicating OCC=2 or 4, and the PT-RS informationof the interference signal. The multi user MIMO can multiplex up toeight layers in the DMRS configuration type 1 and 12 layers in the DMRSconfiguration type 2. Therefore, the maximum number of interferencelayers is seven layers in the DMRS configuration type 1, and 11 layersin the DMRS configuration type 2. Thus, for example, in a case thatthere are seven bits in the DMRS configuration type 1 and 11 bits in theDMRS configuration type 2, the presence of interference can be indicatedfor each of the DMRS port numbers that are likely to interfere with. Ina case that there are 14 bits in the DMRS configuration type 1 and 22bits in the DMRS configuration type 2, the presence of interference andthree types of modulation schemes (e.g., QPSK, 16 QAM, 64 QAM) can beindicated for each of the DMRS port numbers that are likely to interferewith.

Note that cancellation or suppression of the interference signal can beachieved by canceling or suppressing a dominant portion of theinterference signal without canceling or suppressing all theinterference layers. Accordingly, the base station apparatus cantransmit interference signal information for some interference layers.In this case, the amount of control information can be reduced thantransmitting the interference signal information for all interferencelayers. The base station apparatus can configure the maximum number ofinterference layers with higher layer signaling. In this case, the basestation apparatus transmits interference signal information on theinterference layer less than or equal to the maximum number ofinterference layers. At this time, the interference signal informationincludes information of DMRS ports less than or equal to the maximumnumber of interference layers. As a result, tradeoffs in the effects ofinterference cancellation or suppression and the amount of controlinformation can be considered depending on the maximum number ofinterference layers. Note that the base station apparatus may configureDMRS port groups which may be interference, with higher layer signaling.In this case, the maximum number of interference layers can besuppressed and the DMRS port numbers that can be interference can beindicated. The base station apparatus may configure DMRS CDM groupswhich may be interference, with higher layer signaling. In this case,the maximum number of interference layers can be suppressed and the DMRSport numbers that can be interference can be indicated. The number oflayers that can be multiplexed varies depending on the DMRSconfiguration type or OCC=2 or 4. Accordingly, the maximum number oflayers can be associated with the DMRS configuration type that can besupported or OCC=2 or 4. In this case, the amount of control informationcan be reduced. For example, the maximum number of layers 4 can indicateOCC=2 in the DMRS configuration type 1. For example, the maximum numberof layers 6 can indicate OCC=2 in the DMRS configuration type 2. orexample, the maximum number of layers 8 can indicate OCC=2 or 4 in theDMRS configuration type 1. For example, the maximum number of layers 12can indicate OCC=2 or 4 in the DMRS configuration type 2. Note that thecandidates for the DMRS port numbers of interference varies depending onOCC=2 or 4. For example, in a case of OCC=2 in the DMRS configurationtype I, the MARS port numbers to be interference are DMRS port numbersthat are not used for the terminal apparatus itself among the DMRS portnumbers 1000, 1001, 1002, and 1003. In a case of OCC=2 in the DMRSconfiguration type 2, the DMRS port numbers to be interference are DMRSport numbers that are not used for the terminal apparatus itself among1000, 1001, 1002, 1003, 1004, and 1005.

The base station apparatus can classify the assistance information fornotifying the terminal apparatus into the first assistance informationand the second assistance information, and can set different values tothe number of information included in the first assistance informationand the number of pieces of information included in the secondassistance information. In other words, the amount of informationrelated to the first interference signal notified by the base stationapparatus with the first assistance information can be configured to begreater than the amount of information related to the secondinterference signal notified with the second assistance information. Forexample, the base station apparatus can notify information indicatingthe modulation order of the interference signal and the DMRS port as thefirst assistance information, and can notify information indicating theDMRS port as the second assistance information. By controlling in thismanner, the base station apparatus suppresses the overhead in accordancewith the notification of the assistance information, and the terminalapparatus uses the first assistance information and the secondassistance information to generate the receive spatial filter withprecision in consideration of the first interference signal and thesecond interference signal, while generating a replica signal of thefirst interference signal having a large interference power. In thisway, it is possible to perform a non-linear interference canceler.

Note that the assistance information that the base station apparatusnotifies the terminal apparatus may vary depending on the frequency bandin which the base station apparatus configures the component carrier (orBWP). For example, the base station apparatus is likely to transmitPT-RS in a case of performing high frequency transmission. Thus, thebase station apparatus can classify frequencies at which componentcarriers may be configured into two frequency ranges, and, with respectto the frequency range 1 (FR1) including lower frequencies, set theamount of information of the assistance information associated with thecomponent carrier that is configured to the frequency range 2 (FR2)including higher frequencies to be greater than the amount ofinformation of the assistance information associated with the componentcarrier configured to the frequency range 1. For example, in a case thatthe base station apparatus performs communication with the FR1, theinformation on the PT-RS is not included in the assistance information,and in a case that the base station apparatus performs communicationwith the FR2, information on the PT-RS is included in the assistanceinformation.

The PT-RS is transmitted for each UE. Accordingly, in a case that thePT-RS is transmitted, the terminal apparatus can recognize the number ofPT-RS ports as long as the number of UEs to be multiplexed can be known.Since the PT-RS ports are associated with the DMRS ports, controlinformation increases as the number of PT-RS ports increases. Thus, in acase that the base station apparatus configures the maximum number ofinterference UEs by the higher layer signaling, the number of PT-RSports can be limited, and the amount of control information can besuppressed.

Since the presence of the PT-RS is related to the modulation scheme(MCS), the modulation scheme candidates can be limited by the presenceor absence of the PT-RS, For example, in a case that the base stationapparatus configures the PT-RS configuration, and in a case that thePT-RS is not transmitted, the modulation scheme of the interferencesignal can be determined to be QPSK, and in a case that the PT-RS istransmitted, the modulation scheme of the interference signal can bedetermined to be 16 QAM, 64 QAM, or 256 QAM. Note that. the PT-RS islikely to be transmitted in a high frequency band. In the high frequencyband, since the modulation order tends to be low, the modulation schememay be QPSK in the case of multi user transmission in the high frequencyband frequency band of 6 GHz or higher). In multi user transmission withthe large spatial multiplexing order, the modulation scheme may be QPSKsince the modulation order tends to be low. For example, in a case thatthe maximum number of interference layers or the maximum number ofinterference UEs exceeds a prescribed number, the modulation scheme maybe QPSK. In a case that the modulation scheme is QPSK, the PT-RS is nottransmitted, so the associated control information can be reduced.

The presence or absence of the PT-RS depends on the number of RBsallocated. In a case that the number of RBs configured to the terminalapparatus is less than a prescribed value (e.g., 3), the base stationapparatus does not configure the PT-RS to the terminal apparatus.Therefore, in a case that the number of RBs allocated to theinterference signal is less than a prescribed value, the terminalapparatus can perform the interference suppression processing assumingthat the PT-RS is not configured for the interference signal. In orderto suppress the overhead related to the notification of the PT-RSconfiguration information, in a case that the value of the configuredtime density, frequency density, or the values of both of the PT-RS isgreater than or equal to a prescribed value, the base station apparatusmay not include the PT-RS configuration information in the assistanceinformation. Note that the time density of the PT-RS depends on the MCSconfiguration. In other words, the base station apparatus can beconfigured not to notify the terminal apparatus of the PT-RSconfiguration information associated with the interference signal, in acase that the MCS configured for the interference signal is greater thanor equal to a prescribed value. The frequency density of the PT-RSdepends on the scheduled bandwidth. In other words, the base stationapparatus can be configured not to notify the terminal apparatus of thePT-RS configuration information associated with the interference signalin a case that the bandwidth configured for the interference signal isless than a prescribed value.

Note that the base station apparatus according to the present embodimentcan determine the MCS to be configured to the PDSCH by reference tomultiple MCS tables. Thus, in a case that the interference informationincludes an MCS, the base station apparatus may include informationindicating the MCS table referred to by the index indicating the MCS inthe interference information. The terminal apparatus may perform theinterference suppression processing assuming that the index indicatingthe MCS associated with the interference signal refers to the same MCStable as the MCS table referred to by the index indicating the MCSconfigured to the PDSCH for the terminal apparatus itself. Similarly,the base station apparatus can include information indicating a codebookreferred to by the index indicating the PMI in the interferenceinformation, and the terminal apparatus can perform interferencesuppression processing assuming that the codebook referred to by theindex indicating the PMI is the same codebook as the codebook referredto by the PMI notified to the terminal apparatus itself.

In a case that the base station apparatus configures the PT-RSconfiguration and the configuration of the multi user transmission, theterminal apparatus may assume that the number of front-loaded DMRSsymbols is one (OCC=2). In this case, the number of DMRS ports and portnumbers that are candidates for interference can he limited by the PT-RSconfiguration. In a case that the base station apparatus configures thePT-RS configuration and the configuration of the multi usertransmission, and that the number of front-loaded DMRS symbols addressedto the terminal apparatus itself is two, the terminal apparatus mayassume that there is no inter-user interference.

In order to suppress control information related to the resourceallocation of the interference signal (addressed to other apparatuses),it is desirable that resource allocation addressed to the terminalapparatus itself is included in resource allocation of the interferencesignal (addressed to other apparatuses). Accordingly, in a case that themulti user transmission is configured, the terminal apparatus assumessome or all of the same PDSCH mapping type, the same DMRS configurationtype, and the same number of front-loaded DMRS symbols in theinterference signal and the terminal apparatus itself.

Note that the frequency band used by the communication apparatus (basestation apparatus and terminal apparatus) according to the presentembodiment is not limited to the licensed bands and unlicensed bandsdescribed heretofore. Frequency bands to which the present embodiment isdirected include frequency bands called white bands (white space) thatare not actually used for the purpose of preventing interference betweenfrequencies or the like even though the permission of use is given tospecific services from the country or the district (e.g., frequencybands that are allocated for television broadcasting but are not used insome regions), or shared frequency bands (licensed shared bands) thathave been exclusively assigned to particular operators, but are expectedto be shared by multiple operators in the future.

A program running on an apparatus according to the present invention mayserve as a program that controls a Central Processing Unit (CPU) and thelike to cause a computer to operate in such a manner as to realize thefunctions of the above-described embodiment according to the presentinvention. Programs or the information handled by the programs aretemporarily stored in a volatile memory such as a Random Access Memory(RAM), a non-volatile memory such as a flash memory, a Hard Disk Drive(HDD), or any other storage device system.

Note that a program for realizing the functions of the embodimentaccording to the present invention may be recorded in acomputer-readable recording medium. This configuration may be realizedby causing a computer system to read the program recorded on therecording medium for execution. It is assumed that the “computer system”refers to a computer system built into the apparatuses, and the computersystem includes an operating system and hardware components such as aperipheral device. Furthermore, the “computer-readable recording medium”may be any of a semiconductor recording medium, an optical recordingmedium, a magnetic recording medium, a medium dynamically retaining theprogram for a short time, or any other computer readable recordingmedium.

Furthermore, each functional block or various characteristics of theapparatuses used in the above-described embodiment may be implemented orperformed on an electric circuit, for example, an integrated circuit ormultiple integrated circuits. An electric circuit designed to performthe functions described in the present specification may include ageneral-purpose processor, a Digital Signal Processor (DSP), anApplication Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA), or other programmable logic devices, discrete gatesor transistor logic, discrete hardware components, or a combinationthereof. The general-purpose processor may be a microprocessor or may bea processor of known type, a controller, a micro-controller, or a statemachine instead. The above-mentioned electric circuit may include adigital circuit, or may include an analog circuit. Furthermore, in acase that with advances in semiconductor technology, a circuitintegration technology appears that replaces the present integratedcircuits, it is also possible to use a new integrated circuit based onthe technology according to one or more aspects of the presentinvention.

Note that the invention of the present patent application is not limitedto the above-described embodiments. In the embodiment, apparatuses havebeen described as an example, but the invention of the presentapplication is not limited to these apparatuses, and is applicable to aterminal apparatus or a communication apparatus of a fixed-type or astationary-type electronic apparatus installed indoors or outdoors, forexample, an AV apparatus, a kitchen apparatus, a cleaning or washingmachine, an air-conditioning apparatus, office equipment, a vendingmachine, and other household apparatuses.

The embodiments of the present invention have been described in detailabove referring to the drawings, but the specific configuration is notlimited to the embodiments and includes, for example, an amendment to adesign that falls within the scope that does not depart from the gist ofthe present invention. Various modifications are possible within thescope of the present invention defined by claims, and embodiments thatare made by suitably combining technical means disclosed according tothe different embodiments are also included in the technical scope ofthe present invention. Furthermore, a configuration in which constituentelements, described in the respective embodiments and having mutuallythe same effects, are substituted for one another is also included inthe technical scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be preferably used in a terminal apparatus anda communication method.

1-4. (canceled)
 5. A terminal apparatus configured to communicate with abase station apparatus, the terminal apparatus comprising: radioreception circuitry configured to receive: downlink control information(DCI), a first predetermined downlink signal and a second predetermineddownlink signal, at least one of a first physical downlink sharedchannel (PDSCH) and a second PDSCH, and a first demodulation referencesignal (DMRS) and a second DMRS; and signal detection circuitryconfigured to perform a demodulation of at least one of the first PDSCHbased on the first DMRS and the second PDSCH based on the second DMRS,wherein the first predetermined downlink signal is a first channel stateinformation-reference signal (CSI-RS) or a first synchronization signalblock (SSB), and the second predetermined downlink signal is a secondCSI-RS or a second SSB, the DCI includes: antenna port informationindicating one or more DMRS antenna ports, and a first transmissionconfiguration indication (TCI) and a second TCI, an antenna port usedfor transmitting the first DMRS and an antenna port used fortransmitting the second DMRS are included in the one or more DMRSantenna ports, and each of the one or more DMRS antenna ports isincluded in a first DMRS antenna port group or a second DMRS antennaport group, the first TCI indicates a quasi-colocation (QCL) between thefirst predetermined downlink signal and the first DMRS, and the secondTCI indicates a QCL between the second predetermined downlink signal andthe second DMRS, and in a case where the one or more DMRS antenna portsare included in only one of the first DMRS antenna port group and thesecond DMRS antenna port group, the first DMRS and the second DMRS areincluded in the one of the first DMRS antenna port group and the secondDMRS antenna port group, the first PDSCH and the second PDSCH includesame downlink data, the radio reception circuitry receives: the firstDMRS based on the first TCI and the first predetermined downlink signal,and the second DMRS based on the second TCI and the second predetermineddownlink signal, and the signal detection circuitry performs: ademodulation of the first PDSCH based on the first DMRS, and ademodulation of the second PDSCH based on the second DMRS.
 6. Acommunication method for a terminal apparatus configured to communicatewith a base station apparatus, the communication method comprising:receiving: downlink control information (DCI), a first predetermineddownlink signal and a second predetermined downlink signal, at least oneof a first physical downlink shared channel (PDSCH) and a second PDSCH,and a first demodulation reference signal (DMRS) and a second DMRS; andperforming a demodulation of at least one of the first PDSCH based onthe first DMRS and the second PDSCH based on the second DMRS, whereinthe first predetermined downlink signal is a first channel stateinformation-reference signal (CSI-RS) or a first synchronization signalblock (SSB), and the second predetermined downlink signal is a secondCSI-RS or a second SSB, the DCI includes: antenna port informationindicating one or more DMRS antenna ports, and a first transmissionconfiguration indication (TCI) and a second TCI, an antenna port usedfor transmitting the first DMRS and an antenna port used fortransmitting the second DMRS are included in the one or more DMRSantenna ports, and each of the one or more DMRS antenna ports isincluded in a first DMRS antenna port group or a second DMRS antennaport group, the first TCI indicates a quasi-colocation (QCL) between thefirst predetermined downlink signal and the first DMRS, and the secondTCI indicates a QCL between the second predetermined downlink signal andthe second DMRS, and in a case where the one or more DMRS antenna portsare included in only one of the first DMRS antenna port group and thesecond DMRS antenna port group, the first DMRS and the second DMRS areincluded in the one of the first DMRS antenna port group and the secondDMRS antenna port group, the first PDSCH and the second PDSCH includesame downlink data, the first DMRS is received based on the first TCIand the first predetermined downlink signal and the second DMRS isreceived based on the second TCI and the second predetermined downlinksignal, and a demodulation of the first PDSCH is performed based on thefirst DMRS, and a demodulation of the second PDSCH is performed based onthe second DMRS.